My GSX runs about 60 to 65 on a good day but I think your boat is a little heavier than mine. I am also not sure of your engine but mine is 110hp. If is is the 110hp engine it's a great engine and should give you little problems. Enjoy, Craig
P.S. I wouldn't worry about red line as the factory sets it and you can't overrev it. I mean to say the factory has a limiter on it that is set so you can't overrev it.
my gtx with a fresh rebuild got to 54mp/h on the gauge and maxed out rpm at 6850. Who knows how accurate the speedo is though.I had a nujet impeller which increased top speed but bottom end was off a bit. I sold the gtx before i put my solas prop on.