1989 scarab excel 21 top speed ?? what should it be???

[Wellcraft2189]

Hi everyone, in new to boating and just picked up a 1989 scarab excel 21 with a blown up 350 mag engine. I just installed a remain 280hp marine engine and took her out for a test ride, after 5 hours of light driving I opened it up and got a shifty 32mph with 3 people in it at 4800 rpm (I had more throttle to go ) the engine let me go to 5300 but that's a no no anyway I then went back and realized it had a 14.25 17 pitch aluminum prop on it so I did some reading and put a 14.25 21 pitch aluminum prop and reran it topping out at 39 mph at 4400 wot scratching my head I checked out the upper drive only to realize it had a 1.98 ratio drive !!!!! Fml I found a used 1.50 ratio drive and tested again it wouldn't even plain out so I checked my carbon to insure i was getting wot and checked my ignition Timing and realized it needs more timing 5 min later its quickly up on plain and trimmed out i hit 48 at 4500 and trimmed it hits 50mph at 4600 rpm

My question ... I feel like I should get more mph out of this boat or can get more ?!?! Should I try stainless prop 21 pitch or should I try a 23 pitch ? Ive heard of people getting almost 60 mph with these boats ....

[mikem8560]

deffinatly get a SS prop as far as pitch I cant say there are shop that will let you try different props