Go for 17" pitch ybut ou will lose on top end. What is the boat weight? It must be top heavy.
I have supper acceleration - even going from 4500 revs to 5800 revs -and 52-57 knots at WOT (depending on sea state and number of people on board) with a Yamaha 21" Pro.
Why you don't use the Yamaha standard SS prop that is designated for this engine?
To find the best test a few (difficult thing to do in Greece I know) and decide which is the best. Can't think that people can actually tell you just like that what is the best prop for your boat unless they have the EXACT
same boat and engine
All the rest is all pies in the sky. Always IMHO
Manos & Family