I was lucky when my mom gave me her 1974 Dart Swinger after the electrical fire. It was a /6 auto but had LBP all around.
The rear end was a 7 1/4 open but had 10 X 2 1/2 drums. I ran that rear end when I took my Ford 9 inch out of my 65 Barracuda. One day it went BANG and was making a grinding noise like bearings so that is when I swapped my 8 1/4 Aspin rear in. The Aspin rear drums were 10 x 1.75. I then took the drums off my 7 1/4 to find the grinding noise was just the left shoe lining had come unbound. I had the 8 1/4 in the car so I just went ahead and put the big brakes on that axle, Backing plates and drums with new 'Leroy' kit and shoes.