Yup I got burned by the shorter replacement pistons thing. Had no idea til I measured once my short block was already back together. I took a wild ass guess as to how much to mill the block and with 0.030 off the block deck my pistons are still 0.180 down
... With an additional 0.070 off the head my engine measured out exactly 8.4:1 when done. Exactly blueprint spec. I was hoping at the time that with making 0.100" of cast iron dust by milling that it would get me to 9:1 or even slightly more. Goes to show how dismal it would have been if id have just bolted it together without any milling.
I have a long drawn out thread about my build in here somewhere from about 4 years ago
mine is also a forged crank block but with a newer peanut plug head so I could eliminate 6 potential oil leaks ( o rings on spark plug tubes) my build is also in a 1/2 ton truck, I built with very similar goals as you appear to want

The 225-1 and 225-2 HD and XHD truck engines, put into much heavier-duty service than the industrial/agricultural applications, had shot-peened cranks and other upgrades. Valve seat inserts weren't on the list. Here're the '66, '70, '74, '75, and '78 225-1 and 225-2 upgrades:

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Too many people who were born on third base actually believe they've hit a triple.

Here's another vote for the OCG 2106R cam. I have it in a very similar truck, an 82 D150 with 833OD, 3.55 gears and 29" tires. I shaved the head .060. added oversize valves, and had a mild cleanup done on it. Offy 4-barrel intake with an AVS2 500 on it, Clifford shorties to a single 2.5" exhaust all the way out. IIRC compression is about 8.4 static, 7.8 dynamic.

This combo is surprisingly strong. If I stick my foot in it the truck can easily get a move on. Driving it mildly is just as good. It pulls from idle to about 4500 which is as far as I'm ever likely to spin it. At 75 MPH I'm turning a little over 2200 RPM, just where I wanted it. YMMV of course, but this truck is a hoot to drive now.

I took a bit of a hiatus from the slant project to get the property and equipment winterized, but it's time to get back to work on the mean green leaning tower of power machine. I'm working on my shopping list for what I'll need for machining and reassembly.

Is Hughes' Engine the best source for the O/S valves? Seems like ENGNBLDR is out of the game. The camshaft will be from Oregon, of course.
Is there a preferred place to buy all the other stuff (pistons, lifters, valve seals, etc) from or does it matter much? I'm thinking I'll see what the machine shop has to offer and probably go with that.

I'm not opposed to spending money, but I do like to save where I can, are there any components I can confidently reuse? I know to reuse my crank, connecting rods, and rockers, but what about other stuff (lifters, bearings, etc). Also with taking material out of the deck should I be looking at shorter pushrods, with the RV10 cam should I be looking at different valve springs?

I'm going to start measuring bearing surface tolerances, I'm very much hoping that my crank is still within spec. From what I've interpreted from my FSM, connecting rod tolerances should be 0.0005" - 0.0015" and main bearing tolerances should be close to, but not exceeding 0.001", do those numbers seem correct?

I've also decided to try my hand at some mild porting, which is probably going to look more like polishing than actual porting. Is there really any need to go bananas on porting for an engine that's mostly just going to be a road trip rig? I see no racing in this truck's future so I would imagine increasing air velocity at cruise RPM would be more of a priority than maximizing the maximum airflow capacity.