What size props are on the boat? They may not be the original ones.
Mercruiser/quicksilver has a prop calculator on their site that recommends a size based on inputs boat parameters.
You are about a 1000 rpm short of the WOT for these engines. If the bottom clean of marine growth as this will greatly impact performance?
1997 2400 SCR
5.7 Vortec / Bravo 2