Wood/wood core props should be run no higher than 850 fps tip speed (That is helical speed, not circular speed. They won't be much different below 100 mph.) Another reason not to go crazy with the RPM on a direct drive installation. You'll probably do fine with a smaller prop at these modest HP levels, even at relatively low airspeeds. What airspeed would you optimize your prop for (and would that be climb or cruise)?