Personally, I wouldn't use a 15 inch prop on that engine, although I would imagine one with a low pitch would turn ok, but the spin up time may be a tad slow due to the size... although I do use an APC 15-10 or 16-8 on my OS 1.20 AX's and turn them at about 9,500 RPM with no sweat.

The transition time with that engine is perfect with those size props, and you can imagine that it has pretty good vertical performance on both planes. (Venus II and Excelleron 90, both are pattern planes, about 9.5 pounds or so).

I use the OS .75 AX on my Skylark 70 and it too performs without any problems what-so-ever. I believe I'm turning a 14-8 or so on that plane.

CGr.