Are you sure that is the correct distributor cap for your motor.-----Perhaps another case of --" they look the same"----But are not the same.----Put the old cap on and test run ?
There have been issues with crankcase sealing rings.----Results in low crankcase compression.----Post the actual cylinder compression values.-----That may offer a clue.---Yes, you can put a PRESSURE gauge on the port to see what happens.----The fuel pump does NOT run on vacuum !
The fuel pump runs with the PRESSURE from crankcase compression.----That is not the same as compression in the cylinder !-----There may be an issue with crankcase compression and fuel pump does not work !-----Mix the fuel at 50:1 in the portable tank.----Have your assistant operate the manual...
Friends of mine had one of these motors on a 17' deep V boat.----Skied many miles behind it.----Used to pull 2 skiers out of the water with slalom skis.----A real powerhouse.----Take starter apart for inspection.-----See what it needs.
High speed jets are an orifice plug.-----Not adjustable.----Perhaps you can experiment with different jets to compensate for fuel.----And local atmospheric conditions.----If fuel consumption is a major concern ,this is not the motor for your friend.
????-After the pump that hose does not pull air in.------The earlier V-4 models mounted the pump on the carburetor air box.----They needed a third nipple and hose to provide a PRESSURE pulse to the pump.-----These pumps are very reliable and very simple.