If you are using stock replacement cast pistons (Badger or Silv-O-Lite) I'd say 6000 is about the max if long term reliability is important. You will be intake limited by then anyhow.
I agree. Break in the engine with some driving around town for a few hundred miles and enjoy the car before racing it. I assume you used molly rings. Just know there quick seating. Change the oil @ 50 miles and go to the track.
daredevil said
6500 with cast crank and stock rods is where i,d set the rev limiter. is your cam still in powerband that high?