onehundred80, the bigger crank won't allow a stock water pump pulley because of how close they are to each other. Forget the water pump RPMs, there's no room or option but to go smaller. I made 3 aluminum water pump pulleys that are 12-16mm smaller than stock and they're working fine on all the cars.

No2fast, look into Mustang Cobra or MB 55K crank pulleys. Same design you described and available in many different sizes. Tighed1 runs a 192mm crank pulley....nucking futs!