My take on all this is, why not find a '69, or so, B-body housing, remove the spring pads, and re-weld them 1/2" EACH, inboard?
Then, you only have to find some 4.5" bolt circle wheels with 4.5" backspacing and you have a rear end that is all MoPar, and has the right tread width (that's what they used to call the center-to-center distance between wheels) for an A Body....
This gives you a drop-out center section, and all MoPar parts... arguably as strong as a Ford 8.8"...
Just a thought.
B Body rear housings are not as expensive as A Bodys, I think, and are easier to find.
Just make sure it came from the right year B-Body... I THINK '69-'72, but don't take that to the bank... I could be wrong on that.
