Given the recent posts on certain types of posts I am not sure if you are serious or not
but in case you are... You might be better off to just purchase an offy dual intake. I have one on my dart, several others on the list also run one and others are building them up. Given that you mentioned you already have holleys, just make certain that they are exactly the same model numbers with the same jets and linkage hookups (some look the same but have different internals and also you need to make sure your accelerator hookups are of equal distance from the butterfly shaft).Use the search and look for "offy dual" and you will get a lot of information from other list members who have this setup and or have contemplated it.
Here are some shots of my setup if it helps any, there are more on my website under the Dec 04 photo group(see my sig)
http://dk.favorofareply.com/other/dart/ ... 018_sm.JPG
You will also find pictures of 63Dart and "Doctor Dodge"'s setups by searching the slantsix site, both are very nice installations.