I am in the process of completing my 67 and am down to the front brakes. I have a completely restored 4 piston setup, and also a later single piston setup. Is one inherently better than the other?

Hands down use the single piston stuff, doesn't leak, easier to get rotors. If you are going for a 100 point resto then use the 4 piston stuff, but if you plan are driving on a semi regular basis single is better.

The 4 piston stuff can be a nightmare if the rotors are out of round. They do not work any better than the later single piston set of. If they were great, why did GM go to the single piston in 69. Keep the 4 piston calipers and brakets on the self and put the easy to use single pistons on and enjoy.