what axles do you have? stock A-body? stock A-body housing? did you have one cut down to A-body specs?
as long as you have axle with the large brake offset,B-C-truck 8 3/4 axles,or moser axles or some other after market axles
7 1/4 wont work and the skinny A-body 8 3/4 brakes wont work with the large brake offset axles
any brake set up of a 8 3/8,9 1/4,8 3/4,9 3/4
A,B,C-body and truck will work
I used 73 bp and 11x2.5 brakes from a 73 newport on my 68 dart going from 7 1/4 to 8 3/4,I did up to the largest wheel brake cyls
11s are a little big/heavy,but the stopping power over the 10s was very noticable with hard braking,auto-x style,almost no fade
I had the large 12" rotors from an R-body on my A-body spindles with a MP 4 bolt mc to 2 bolt alum mc adapter with a 79 truck alum mc,all manual brake even had air scoops on the front dust sheilds for cooling of the rotors
braking power is transforming friction into heat,bigger is better