I have a 1984 Thundercraft 16 ft with a 1979 140 horse Merc on it. Presently I'm running a 15 pitch prop but I have a 17 pitch as a spare. Would the 17 be a better choice. I know I should go by my tach but I have to find a harness for it from the controls to the tach. Would it rev higher at WOT...