70 coronet 8.75 in 70 dart

At this point. If you narrow the B body housing to the correct A body width, moved the spring perches, and used the A body axles. The only things you would need to get would be A body 8 3/4 backing plates and drums. The center section will swap in no problem

And if this is all done and correct I should have no issue with wheels providing they are the correct bolt circle?

And obviously not MASSIVE etc.