Congrats on purchasing a great boat and welcome to Team Talk.
For starters, your engine is a 351 Windsor.
To remedy what sounds like a rich situation, I would hit the basics first:
Check spark plugs...might be pretty black by now.
Do you still have points.......if so confirm correct dwell - don't rely on point gap
Confirm choke opening fully by 90 seconds
Turn mixture screw in until lightly seated and count number. Should be close to 1 1/2 turns
Confirm base timing at 10 degrees or whatever spec says
Clean flame arrestor.
With all that done, I suspect that you have too rich a power valve in your carb. Should be 2.5 though some carb numbers spec a power valve closer to 5.0
REBUILDING HOLLEY MARINE 4160 CARBURETORS - $199 DELIVERED
GENUINE MARINE HOLLEY KIT USED - INCLUDES POWER VALVE UPDATE
LED TRAILER LIGHTS, LUG NUTS SPARE TIRE CARRIERS, SAFETY CABLES....
Originally Posted by Bouyhead
Installed my carb that was rebuilt by thatsmrmastsercraft, Thanks Peter!! Hot or cold this boat starts and runs like it fuel injected.