Yes, the engine side clutch half is available for 5/8" and 3/4" shaft diameters, at least. Deejay would know of sources for other sizes, if any exist.

Electric motor reconditioners commonly offer keyway repair services [weld and re-machine]; it would be worth calling a couple, since you have the damaged crank out of the engine. Not much different to working on a leccy motor shaft, really.

Cheers,
Gadge

"ODK Mods can explain it to you, but they can't understand it for you..."

"Crazy can be medicated, ignorance can be educated - but there is no cure for stupid..."