Maybe not the best choice but I've always used 24-10 props on the Q75 .... mostly Xoar props since they have been available, Menz before that. No experience with 3 bladed props. The engine doesn't have quite the power of the newer 75 - 80 engines so don't expect to be pulling the "big wood" with this engine. Also, it seems to like to turn up a bit as you would expect for a chainsaw conversion. No idea on prop RPM as I have never tached this engine.