Theories on my A body

To be honest if someone installed a 360 I would just leave it be and clean up their mess. I wouldn't put a 4.0 in it either. After fixing their mistakes in the engine bay then I would move on to the suspension. As far as upgrades go, that is all dependent on how powerful an engine you have or build. Stiffer torsion bars, Size of brakes, etc. are based on weight of engine and amount of power you need to stop or put to the ground. Make a reasonable plan and then start researching it. For a basic or mild 360 I have seen guys running Ford Explorer rearends to have the ability to run rear disk brakes. Otherwise just look for a factory 8 1/4 or 8 3/4 rearend. There are brake adaptation kits from Wildwood that bolt right on. For front brakes a lot of people use 73 and up front disk brakes from an A body or early 80s diplomat.