RE: I could use some expert advice.
engine runs no load full fuel at 3200 rpm
@ 2750 rpm I can cruise at 6.0 knots max speed on a good day is 6.2 knots at 3100 rpm full fuel.
Running max load of 3100 with a no load rpm of 3200 is about normal.
Only gaining .2K for over 300 rpm shows you are getting all the speed the hull is capable of .
A far larger engine would be required to go much faster.
Personally I would not cruise above 2700 for long periods of time.
It would be interesting if you would publish a speed/rpm chart , as perhaps a different prop would cruise at the same 6K but at say 2200 , for better engine efficiency and service life.