11x7 is pretty good all around prop on a .61 12x6 would be my second choice for your plane. Think about pitch like this. Get in a manual transmission car. Take off in first and it will accelerate quick but top speed is not much. Take off in second and it will not accelerate as fast but top speed will be higher. 1st gear is the 4 pitch prop. 2nd gear is the 8 pitch prop. Ideally you want the load on the engine to be similar. So the 4 pitch prop can be 13" long (13x4) but the 8 pitch prop can only be 10" long (10x8).

David