Just depends on how much pain your wallet can take.  It really isnt a design that lends itself well to high rpm or high horsepower. Bearing speeds get insane and not a lot of aftermarket support either.  But Bulldog, Rockett and others can build you 500+ if'n you really want it.

Sent from my SGH-T999 using SoCal Jet Boats mobile app

So 30 over would be a real safe number and allow more power and torque. Plus it would be a little easier on the wallet