Sorry, not enough info to give any advice as I don't have that exact boat/engine.
Run the boat, check the prop size, make a note of the max revs and what revs you are cruising at.
I wouldn't be playing with props unless you have a problem to fix and you can only get that info when you run it. I don't know why your friend thinks you won't like the top end, it will likely be very close....except you will be able to hear yourself now!
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