just rebuilt runs bad

I would think to look at those non-adjustable rockers too. I can't stand running them with ANY aftermarket hot cam. It just bugs me. Those are for grocery-getters. Second, there's always the possiblility that the harmonic balancer outer ring has slipped and the timing mark is incorrect. And then I'd think about vacuum leaks around the carb/intake manifold or even the brake power booster (if it has one). The fact that you mentioned "pinging" bothers me (if it actually WAS pinging and not valvetrain sound).