Vacuum advance units aren't rocket science- - - - -why couldn't a more available item like one for a small block Chevy V8 be adapted to the stovebolt linkage? I'll bet I could spend an hour or two with a drill press, a hacksaw, and a few sheet metal screws and bring some of those dead ones back to life! I believe the stroke could even be made adjustable to fine tune the total degrees of advance in the process!
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!