Your gonna want a motor that will rev safly to 6500 at least, it dosen't matter how much power it has in the water just high Rpms, our boat has a 488 Mercruiser I/O and it has 185 Hp and revs at about 4800 at 40 MPH ( top speed( 23' glass cabin cruiser boat ). you just need somtin that's gonna take the revs, boat's do rev that high, it's not unusual.