Mark, I removed the starter gear and machined the rotor so it would push further onto the crank taking up the space left by the gear, I trimmed it down a bit but not much so it will still charge, I could probably have made it a lot smaller because I have no starter and hence a small battery.
I think therre is room to trim the othet side too, If you have a boywer ignition you can trim the case back because you don't need the space for the advance mech, also the clutch cover can be removed and the underlying case can be spruced up a bit, starting by removing the three legs that hold the chrome cover on, but trimming the left side does balance the motor:
