use an 11x7 three blade.

If you're a beginner Master Airscrew 3-blades are the way to go as they are very flexible. This doesn't really lend itself well to performance though unfortunately.

If you're not a beginner and have no problems landing, use an APC or a Graupner prop. Very good quality props. Graupner might even be better than APC.

A .61 uses a 12x6 two blade, which transfers to a 11x6 or a 12x5 three blade. I haven't found these sizes yet, so the 11x7 is the way to go.