Sheared the cast-in key on one flywheel and decided that I would like a better mating of the surfaces so lapped the taper area with some valve grinding compound. Hasn't slipped yet.
You might want to make some reference index marks on case and flywheel for TDC before pulling key.

Looking from the front of flywheel, rotating the flywheel CCW should advance the timing.

Set this one at 28 degrees w/ CH Ign. One tank ran still working on carb settings..