I Have a repowered 1974 26 foot Tollycraft. 454 340HP. Borg and Warner 1:1 Velvet drive, straight shaft. 24 ft at the water line. 9000 lbs. Has anyone had this configuration and have any prop suggestions. Currently has a Nibral 3 blade 14x8 cupped. It's not doing the trick. 17 knots top speed...