2004 Hewes Redfishes 21 Suzuki 200hp SS Prop Help

[Capnjefe034]

I bought this 2004 Hewes Redfishes 21 about a year and a half ago as a project boat. I am getting close to having everything complete, but one of the last head aches is getting the right prop for the new Suzuki 200hp SS (year 2020) I had installed about a year ago. The previous motor on the boat was a 200hp Yamaha OX66 and it had a 21 pitch 4 blade prop. The boat came with the blown engine so I never had experience with the performance of this setup.

With the old prop that came with the boat (21 pitch 4 blade smaller diameter), I am getting between 5300-5600 max rpm and top speed of about 45mph depending on how the boat is trimmed out (considering both motor and boat trim). This prop cavitates before I get on plane in all positions accept when the motor is trimmed all the way down in its lowest position. 

I have been working with a semi local prop shop to find something else that would work for my situation. The prop they gave me to try is a MS275 OFX4R19P. This prop performs much better, but still isn't performing flawlessly. I hit 6000 RPM and 50mph with it now and get on plane much better. The only problem I still have is that it cavitates when I hit 4000 RPM in all positions ACCEPT when the motor is trimmed down to its lowest position whether the jack plate is all the way down or up. 

The prop guy things it might be because the back of the hull as a small step that would be causing this problem or that the prop might need more cup, but as I understand it, this prop comes with quite a bit of cup.

Any experience or comments from others running a Redfisher 21 would be very helpful!