Welcome to CSC 76dream
Something is not kosher here. Are you running a aluminum or a SS prop [img]/images/graemlins/confused.gif[/img] I was running 14 3/4 x 17 many years ago on a 200hp Johnson on my 23'. I was hitting around 5500 at WOT. When I repowered to a 222hp Johnson I switched to a 14 3/4 x 19 Viper SS. I am now using the same prop on my 1999 250hp Johnson. I'm topping out at 5800 WOT.
Depending on your fuel tank size here's the specs:
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http://www.classicseacraft.com/brochure/SF23Specs.jpg