6.2 into a 79 Trans Am

Hi all, new to the forum but not to the 6.2. Anyway I have gotten a deal on a 79 Trans Am with no radiator engine or trans. Otherwise complete, rough but complete. I have a 6.2 and th400 from an 83 1 ton that I will be putting in just to have something different and to play around with fuel mileage. Not sure which trans to use in the long run probably a 700R4 or a 5 or 6 speed manual. I am planning to use the 4 core radiator for the TA and an external oil cooler and the hydroboost from the truck any other things I need to think snout?