A single engine v drive will have a standard rotation direction.(clockwise when viewed from the front of the engine) Now if it's in flywheel forward,(CCW from the flywheel end) and running through a v drive,(which changes direction of rotation) then you will need a Left rotating prop, and vice virsa for driving off the crank snout, a right rotation prop. As far as the forward/reverse ratio, it would depend on which gear box you have, although I would guess the reverse is quite a bit lower geared than forward, to prevent swamping the boat in reverse........MP