The .46 is not excessive on the Four Star 40. It will do very nicely. Stick on an APC 12.25 X 3.73 and it will just about torque roll if you get good enough. (span is a bit much for torque rolls on a 12 inch prop)

The .52 4-stroke is about the same power as the .46. A .72 is really too much for the 40 size. (its the recommended 4-stroke for the 60 size)