And you went the WRONG way. The 17in pitch will get you on plane Faster than a 19in pitch.
You need more test time with THAT prop. It surprises me on your numbers [5950] I would bet the RPM would climb even higher.
By the way that is known as a "Square" prop wen Diameter and pitch match.
4in of pitch should change RPM aprox 800RPM which you don't want..... But the 4th blade will slow that down. How Much will it slow it down? I don't know?
A 4 blade will give you Stern lift Thats a good thing, as all these Parkers suffer from the *** end dragging.
You also need to understand a Suzuki. It's geared lower than ANY other outboard on the market due to it's design. With that comes unique proping. Yamaha proping has no business around a Suzuki.... They are different animals and thus need different proping.
Look at Offset Driveshaft and 1st stage reduction.
https://assets.suzukimarine.com/wp-content/uploads/2022/06/21102258/SZ_150-175-200-A-AP.pdf
With all that said.... It can swing a larger dia prop.... Think of it as larger tires for more traction.