I'm running a gm 350 that puts out about 400hp, but would like to swap it with something that will get my boat to 60+mph (currently running 45 with 70 gallons and 9 passengers at 4600 rpm, #3950 boat with 17 pitch prop on Powell). Anyone have any suggestions to optimize my HP (i'm sure the 400 hP is at 6000+rpm) My boat is rated for 500 horse...