73 BBP disc or 4 piston disc brakes?

Depends on what you want. If it better wheel options then yea BBP, but pattern isn't everything. When you convert with factory stuff you widen the front track. Offset become key and then wheel availability narrows unless you are OK with running spacers or use a narrow wheel and tire up front, depending on your fender clearance and suspension ride height. If its reliability, then the worst thing you can do to any car is let it sit stagnate.