Converting rear drum brakes from SBP to BBP

M67cuda said

A lot of information to digest. I am beginning my build so let me make sure I have this right. I want to go to BBP just for the better options of wheels. For the front my option is to swap the front spindles, rotors and upper A arms from a 73-76 B body? that would have to include master cylinder and proportioning valve? which while I'm there I might as well get the booster (did I miss anything, like linkage)? Now for the rear I can use the axle from the same car but I need to relocate the spring mounts 1/2 inch inboard? If I just want to swap axle shafts I have to drill the drums for BBP? I can't swap drums and backing plates from the donor car and install BBP axles unless I use the axle housing from the donor car, right?

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Couple of things- you need UCA’s from a 73-76 A-body. Not B body. B-bodies use totally different UCA’s. That may just have been a typo.

If you use a 15/16” master cylinder, there’s really no need for a booster, you can run manual brakes. Not a fan of the power brakes on these cars.

Rear axle- I’m not sure what rear axle you’re even talking about. B-bodies used several different widths (and different type axles!). Some can work with A-bodies if you’re talking about a Demon, Dart Sport, Duster, or Barracuda. But some of them are way too wide. All B-body housings will need the perched moves. When you start talking about swapping axle shafts I’m not even sure what axle you’re talking about. You can’t mix and match SBP and BBP brakes and axles.