I also used Joe Gibbs Break-In oil on my rebuild and was happy with the results (the rings seated etc). They also make a special "Hot-Rod" oil, which in addition to having zinc is supposed to stick to the engine parts better so that there's more oil on the moving parts when you first start the engine. It's made for cars that are not used as a daily driver, and it's supposed to reduce wear during those first few seconds of operation. I used the Break-In Oil for the first 500 miles, and I am using the hot rod oil now, but with only ~1500 miles on the rebuild it's hard to say much...
Keith