I am also planning to get the AC ducts in before going too far with the wiring. I am working on getting the side pipe alignment sorted out first, FFR sent me a set of 351 headers that will get here today, we will see if they fit better. Then I will take the body off and open up the passenger foot box to work on the AC system. There should be lots of space behind the dash with the AC unit in the foot box. Your engine fills the engine bay way more than mine and you have much more wiring to fit, some different issues to figure out.