The easiest brake upgrade 8 3/4

As long as the axle offset is set up for the non A body brakes your good.
Any 1965 and up large bolt pattern brake assemblies will work. 7.25, 8.25, 8.75, 9, dana

I have a set of 11x2-1/2 off a 74 B body 8.25 on my 72 Demon's 8.75. I've put 10x2-1/2 from an Aspen/Volare 7.25 on an 8.75. If the backing plate is missing the 5th stud hole just drill it yourself.