It sounds about right for bone stock.
Would like to know what grate is in it.
Yup...
How fast do you want to go?
Lose the rudder, add a Place Diverter (the single most impressive change you can make for the buck).
Lose the anemic vacuum secondary carburetor for a mechanical secondary 850cfm marine
Lighten the interior wherever you can (betting it has plywood everywhere)
Move as much weight to the back as humanly possible.
Make sure the engine compartment is well ventilated, most closed engine compartments run in excess of 130°F, not to HP friendly)
Make sure of the tune i.e.; timing all in at 2500 RPM and max at 36° BTDC, ride plate about 3° up from flat, jetting is at least close, controls are synched correctly (reverse gate out of the way, throttle opens 100% etc.), fuel pressure is adequate.
It is my opinion that 60MPH is what should do.
On an unrelated note, you really need to pull the elbows off the exhaust and replace those gaskets. Looks to me like they are original and need some attention.
With the above changes, you will have a 65 MPH boat. To go faster, you need to lighten the boat by 400#, remove the comfort hook in the bottom, add a loader, a stuffer, and make about another 100 HP. That should theoretically put you at near 70. A lot of money for 5 MPH, but the truth hurts.
If it was my boat, I would add a Diverter, replace the carburetor and go have some fun...
GT
edit; at the very least, make sure you have the light yellow spring in the vacuum pot for the carburetor.
