I run a pro billet and 6al in my 66...I like it and have had no problems. The only thing I would like to see for the pro billet is more selection in advance stop bushings, I think someone was going to market them and they might be available now but I haven't seen them. It's pretty easy to change advance springs on the billet..Not as easy for the stop bushing, but I have done it without pulling the distributor.
Not up on the mallory so this will bump it...