Pro x's should be fine as listed above. I will say that with the compression your looking to run (31 or 33cc domes), should put you well above 190 psi cranking pressure. If you are using pump gas you are border line on having some pre detonation. Forged pistons hold up to a little detonation much better then cast. With either piston make sure to check piston to cylinder wall clearance. May need to hone a bit for the wisecos as they tend to be just bit bigger then oem or prox. I like to see piston to cylinder wall clearance in a recreational open loop water craft cooling system in the .005" to .007". This would not be acceptable to other forms of high performance engines with closed loop cooling systems, but with cooling water as erratic as it is with our stand ups, a little extra clearance doesnt hurt.