As people have alluded to, if you have the crank pulley and the water pump pulley the same size, then they run at the same speed. A smaller pump pulley (or larger crank pulley) will run the pump at a higher speed.

But I agree with Neill above. The biggest issue with the cooling on these cars is the water pump efficiency. I bought a new pump and divider plate for my engine (I'm running the '69 and later 11 bolt on my '68) and the clearance between the divider plate and impeller was almost 1/4"!!! After coming across the Wallace Racing article on desired clearance (there is a post to it in the Hall of Fame section) I massaged the divider plate so the clearance was 0.025". You can imagine how much of a difference that will make in the pump efficiency.

So the reason you have to overspeed your pump is most likely because it is internally bypassing way too much coolant due to larger clearances. Running the pump faster helps that, but it's not correcting the root cause of the issue.