500 cubes with cast iron heads will have a torque peak around 4100 rpm. Max hp will be 1000 to 1500 rpm after that depending on cam and intake and so on. If you put it on the dyno that is what you'll most likely see. The .620 cam will run out of air around 5000 rpm as I said before so peak power will be somewhere around 5000 or maybe a bit higher. I doubt you'll need to shift it much past 5500 rpm.