The worm drives did work well and were very quiet compared to the chain drive. That is a 780 Nova, the last model built '68 to '70. My concern with this gote is the new clutch. The original Bonham clutch was built so it could be put on the motor both ways, with the clutch closing towards the motor or the clutch closing away from the motor. All other belt clutches close towards the motor. The Nova was designed for the clutch to close away from the motor. All nova's that I have seen with after market clutches loose efficiency when the belt twists from the clutch plates moving in opposite directions.