I have a 1970 Fiberform 17' V- Hull. It has a 120 horse 4 cyl outdrive Mercruzer. What size and pitch would be the best for top end speed. The one I have on it now is a 17 pitch 3 blade. It's a dog. Runs about 3000 rpm full throttle around 20 miles per hour. I don't need to spend lots of money for a stanless or equivalant. Thanks for your imput!