Well I ended up with 18/73 a 72 rear would be perfect but I didn’t have one on hand. I’m very impressed with the engine but the Preimere cluch supplied with the package is going in the scrap bin. This is the second premiere clutch I’ve had trouble with they’re won’t be a third. I switched to a Hilliard Inferno with the bully conversion to run a 219 sprocket with a bearing instead of the bushing. Much Much better smoother easier to tune all is well.