Don, here's some food for thought.......I learned to fly on a Falcon 56 & OS40 with a 10x6 prop. I couldn't slow it down for landing - by the time it did slow down I was already past the cut grass and over the tall grass - power up and go around. Time and time again this happened, then my flying buddy said I need to try a different prop. He suggested a 10 x 3 1/2 pitch. The plane didn't go very fast, but it went almost straight up with ease and the best thing - it slowed down for landing. The 3 1/2 inch pitch did the trick. It might be worth the effort to experiment with prop sizes.

Say for instance, if an engine is really happy with a 14 x 8 (add the numbers 14+8=22).........then almost any prop, as long as the diameter and pitch add up to 22 will be happy on the engine........you might have to detune the engine (richen it up) to handle the larger diameters, but the engine will be fine.

Remember, 4 strokes put out nearly 90% of their power even when running very rich.

Just my 2 cents worth. And by the way, you will need to learn the rudder to handle torque on take offs, no matter which engine you use......so start burning more fuel.....I guess you got an extra 2 cents thrown in there, eh!?