Back then they were 440's
We tricked them up with skidoo carbies, and NOS.
The motors were port and polished.
We entered two of them in the Manly to Seebreeze, Sylvania coastal race.
I ran 3rd after difficulties and the other one ran out of fuel just inside Botany Bay.
One thing I do remember is that I could hardly walk for three days after the race. LOL.
When you hit that NOS button you had to hang like all hell and be very careful about keeping the impeller in the water, being a two stroke if you didn't have a load on the impeller you could blow the motor.
We toured the west coast of US with the rig below.
peterp