There would be no point in butchering up a good one, but if anybody has replaced a flywheel for bad starter gear teeth, I'd love to have it for experimenting. With an accurate lathe and a tool post grinder for the final diameter machining, I can't really see why a separate ring gear couldn't be fitted. Once the gear is in place and running true, a few TIG welds would assure it stays put.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!