Dissapointing performance

Yes your converter and rear gears will affect you're trap speed. If it can't get moving off the line it will not show it's potential. BTW the carb and exhaust are to small for that combo and your gears and converter are wrong too. If you're dead set on the gears and converter put a smaller cam in, you'll be much happier. The heads picked up almost 2 mph so it is making more power than before.

BTW where is your initial timing? With that cam it should be 18-22°.