The brake configuration on A-bodies is different from the others, I believe it sticks out less, so you'd have to use brake assemblies from non-A-bodies.
This question used to get asked a lot and the answer was there are some axles that can be cut down and resplined and some that can't. Many of the axles taper too early so there isn't enough material. And I'd never recommend welding on an axle shaft.
