The 46FX will give you better performance, especially in the speed department. Try an APC 10" x 7", and if that doesn't give you enough speed, try an APC 9 x 7. If the 10 x 7 loads the engine too much, and you actually lose speed with the 9 x 7, try an APC 10 x 6 or 11 x 6.

Try the props and don't worry about the ground rpm's too much. The 7" pitch props should unload better in the air, and you may need to go slightly richer on the ground, so that you don't go lean in the air when they unload.