Lookin at this boat has a 502 .30 over victor jr intake 850 dp carb full roller valve train eddie marine exhaust. Individual selling it said it dynoed 643 hp @ 5500. But with a 26 four blade running in the boat he only gets 4800 rpm. Something seem to be off asked if it could be as simple as the tach seller says no. Am I wrong in thinking this motor should pull 5100 to 5300 rpm's with a 1.50 drive & 26 4 blade? please help. I like the boat just dont have the extra time and money to fix it if there is something wrong.