I recently purchased a Maverick 21’ Master Angler with a 200 small block HPDI and it is significantly overproped with a 23" Yamaha pro.
Maverick and Powertech have recommended a 19 or 20" OFX4. Others have recomended the comparable Mercury Rev4.
Before I purchase a replacement, I would like to try and compare. If you have one; I would like to borrow it for a couple of test runs and could return it the same day.
I am willing to leave a deposit for the loaner and a case of beer for your troubles. Any help would be appreciated.
Your WOT looks like you are getting correct RPM. Which bolt hole is your engine mounted to the transom on? It could be that lowering your engine a bolt hole (putting it deeper in the water) would help with the cavitation.
I am no prop expert, but I have moved my engine up and down (on the transom, not just trim) to get it where I liked it. And when the engine was mounted too high, the prop would cavitate like you are describing.