If they are Budd, the calipers will have 4 pistons. Everything is hard to get and $$$$. The 69-73 style is a single piston. 69 to early 72 uses the same wheel bearings as your drum brake spindles do. The late 72 and 73 spindles use bigger bearings and a less expensive unicast rotor but the earlier one isn't that much more and nothing close to what a set of Budd rotors will set you back.

Make sure what you have is in fact for a Cbody. They all look the same to me when they are laying loose on the floor if I don't have a known one to compare.

Kevin