The flywheels I have on hand have teeth that are are pretty much squared-off. It wouldn't hurt to bevel the teeth a little, but the starter drive pinion teeth have a pretty good bevel on them, and a 6V starter moves the drive pinion straight forward as it engages. The 12V drive rotates a little due to a helix built into the drive and the armature shaft.
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!