The boat is 26' LWL, 9.5' Beam, weighs 7000 Lbs (best guess with tender, 4 people, full tanks and lots of beer). Prop is the standard 3-blade 15.5' Dia. x 15" pitch. Drive gear ratio is 1.41:1, and using synthetic oil. I used one of the online prop calculators and at 3500 RPM/26 MPH i have .27 prop slip, and at 4200 RPM/35 MPH with .18 prop slip.

The carb is universally used between a 5.0 thru 7.4L size engines.

Points are new and dwell is steady on the mark.

The only 3 things that I can play with are cam advance, ignition, and carb tuning. Incidentally, the engine likes to run on the hotter side than before, my exhaust manifolds used to be tolerant to touch whereas now they can't. Running with no t-stat it holds at around 120F. T-stat in and it overheats in 3 minutes at cruise. This could be a good clue....