1973 Scamp Brake Question

In 73-76, the upper ball joints were the same for disc and drum, so you don't need those. The hardest disc-conversion parts to find are the spindles, caliper brackets, and dust shields (I've read the dust shields aren't strictly necessary though). If you want a kit, TheRamMan.com has a decent price on a kit that has everything you need. It will include a sleeve that pre-1973 car owners can use on their upper ball joints so they don't have to replace the upper control arms. They also sell rotors with small bolt pattern in case you want to keep SBP. Factory rotors from 73-76 had LBP, unlike the earlier rotors.