20SF w/2013 Yam 150F What Prop is best?

[CaptBill]

Greetings ... Just re-powered my 87 " Voyager" with a Yammy 150 4 stroke ... Voyager earns her living taking couples out to the many reefs around Islamorada Fl. Keys... came with a Reliance Series 14 1/2 17 which works pretty good .... but not getting all RPMs on top ...
Yamaha recommends a Reliance Series 13-3/4 x 19 For a Key West 20 which is about the same size and weight .....
Any Suggestions ?? Thanks!