78 750 KZ primary chain replace

I haven't ever tried what your suggesting,  if it were me, I would do a new starter clutch and if I had any concern at all about the starter gear after inspection,  a new one of those also.  Not a job you want to undertake again shortly after. 

You can try to a light wet (oil) sanding of the surface to re-new the grip. Start with 180, finish with 600

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