Reading the past specs, it's supposed to have a 21p prop but if you're normally hauling around 5 people (I'm guessing H190-H200) mid 40's is all she's going to see. It might go slower with that 21p over the 19. Buy a $100 aluminum prop and try it.
You also gotta remember that 5.0 is very low in power even when brand new. A modern 4.3 V6 is more powerful. It's also nearly 20 years old, so do a compression check it's probably down some horse powers. If you really want some speed and have some cash laying around. That IS a small block ford. Call up Summit Racing or Jegs and have them ship you a few boxes of performance upgrades. Aftermarket heads, good marine cam, high compression pistons, a better intake/fuel system, thru hull exhaust, etc. Get that baby to do 70 with 5 people on board
