I will try to anwser some of your questions. Of course these are my opinions & others may ot agree. But I have been building Turbo street/strip cars sense back in the early 90's.
#1 Yes, if its in good shape in all parts of the engine. There is more stress, but not more than good stock parts can handle.
How much boost? Wrong question. The boost number itself is only a reading of restriction. What matters, is how far you can go without detination. And this will have alot to do with, manifold/header design, fuel induction,turbo, igniton, fuel type,cooling,condision of engine,weight of car,gearing, tuning, weather, and many other things. As a good rule of thumb, you can probably run much more horsepower, than you can achive without going passed the point of detination. In other words, you will have detination problems before you reach any horsepower limits. And the detination limits will end up being you horsepower limits (within reason).
#2 No this is not true in anyway. The results from a turbo system have more to do with the temp of the air, than how much air gets in the engine. Is a IC needed at these low levels, NO, you can get by without it. But a good IC sized right can do nothing but help & give better durability & horsepower for the engine. It will allow you to run more boost with less problems of detination. And even in a low boost setup, it will allow you to push the tuneup & get more power out of the boost you run (more timing,leaner fuel & that gives more HP)
#3 Yes, there is what they call a " Boost referance regulator". It gets a boost signal from the intake side & incresses the fuel pressure when boost climbs. You can even take a normal regulator & drill it to have a boost port & it will make it do this. But I do not recamend this unless you know what you are doing and have expeirance.
#4 Right here is a very good place to start on learning what needs modified on a Holley carb for Blow-Thru.
http://www.hangar18fabrication.com/blowthru.html
Here is a forum with a lot of Blow-Thru carb info. There is a Carb & Boost section that you should read each & every one of the threads.
http://www.theturboforums.com/smf/index.php
#5 If your making enough heat to kill the manny, your engine is probably going to be toast already. One of the main problems in a turbo setup is getting the heat out (out of the cylinder). But still yet, it is the heat & the pressure defirencial ( I know spelling) that makes it work.
The stock manny with a J pipe will work. But it is not going to give you anywhere near the results that a well made header will do. It is also going to limit you on the detination threshhole. In other words make it easy to detinate, because of backpressure & heat being trapped in the cylinder. The exhaust side of the turbo setup limits will hold you back more than the intake side limits.
#6 It is best to get these things there own source. But the oil can be as simple as hooking up to the oil pressure sending unit oil feed. A T fitting will work, but you would want to be sure you used the stright side of the fitting for the turbo. You dont want no 90 degree turns in your oil feed. The return oil feed is even more important. It must be stright & go down hill. It also must inter the engine above the oil level & it is best to be at a piont that does not have windage. Any resistance at the oil return will cause the oil pressure to over come the seals in the turbo & it will start causing smoking problems.
The water side could be taped into something like a heater hose. Like take the pressure side hose & hook to turbo & come from turbo back to where you removed the pressure side heater hose. Just put it in the loop so to say, and be sure it does flow the water. Some heater circuits may have a heater shut off valve that stops the water from flowing through the heater core ( like a car with A/C) and you want to make sure the water flows at all times & there is no valve that will stop this when the ehater is turned off.
#7 It is way to small (both the turbo & intercooler). Two of them could work though, but that is a lot of work. Being worried about the turbo not spooling is the wrong thing to do (within reason). The worst thing you can do is go with to small a turbo. You say, well I only want 7 or 8# of boost, it will be OK, right? But that is not how it works. Remember, boost is only a mesurment of resistance, and not how much power you will have. The exhaust side of that turbo will choke the /6 & cause all kinds of tuning problems & bring in the detination level at a very early time compaired to the proper size turbo. It will keep the heat in the cylinder & cause high EGT's & low RPM's ( lower than you want).
Sale the turbo, and start over. It is a waste of time to use it & will end up causing you to probably blow your engine.
Just something to think about.
Read the info I link to, read it all, then go read some more. There is a lot fo info out there that will help you make the right choices. Learn what you need to make them, and dont expect anyone to make them for you. You will end up on the wrong end of the stick if you dont.
But just a little on how I would build this.
Go buy a GT61 Garrett turbo, they can be had for around $800.00 & will give you a good spool, plus a good power level. The bigger turbo will pump cooler air, this will allow you to reach much better low boost performance because it will make more power before reaching the detination limits. And it will pump more air at the same boost levels as the smaller turbo.
Build a good header instead of using the factory manny.
This will allow better permormance & help keep the back pressure, & heat in the engine down. Which will agian let you reach higher levels of performance before reaching the detination limits.
On the Carberation
This is a tough one. the slant six has a problem with fuel distribution. Which setup to use has not really been worked out. But what ever you use, take very small steps with tuning & boost levels. Read the plugs (all of them after every single change) like you was looking threw you best PlayBoy mags ( if you do that, if not you know what I mean). Doing this will get you there without destroying the engine & allow you to reach very nice power levels without even pushing the system. After the system is made properly the tuning will be the key to success. And you can only push things as far as your worst cylinder will allow you to.
Fuel injection is really the anwser & worth the effort in many ways. It can even be done cheaper than going out & buying a Blow-Thru ready carb system.
The stock engine.
The /6 is a tough little engine, and has some very nice factory stuff in it already. Like the crank is forged, the rods are forged. The pistons are not forged, but they are some of the best factory cast pistons you will ever see. And although I have not proved this, I feel sure they would stand up to 400hp if the setup is tuned right & the cylinder is not let to over heat (inside the combustion chamber, not water temp). Now I am talking, never,ever let it detinate kinda tuning. Even the best pistons on the market will die in a instance if its treated wrong.
There is no doute in my mind that turbo systems on the /6 is the best way to make good power out of them. It can be cheaper, easier on the engine, be much more streetable, and make way more power than big stroker or high compression race type setups. Its just got to be right.
Your build
At the very least, get a turbo that is more to size for the /6. Even if you use the factory exhaust manny, and no intercooler. A GT61 (T4 turbo) on the factory manny is still going to do much better than any overly small turbo setup that can be made. And even in a limited setup like this , 300hp plus on pump gas could be achived at low boost levels
( more than 7psi though) very easy.
Hope this helps, and remember this is only the beginning, there is much more that could be touch on this subject. And I am sure there is some that will dissagree with me., and that does not mean they, or me, are wrong or right. There is just always more than one way to skin a cat as they say.
Jess
PS, I have to go for now, and with this long a post I may need to go over & change some things.
Jess
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