On a scale of 1 to 10, water pump problems would be about a 23! It's more likely you've got bearing troubles or pistons getting tight enough to give the engine a lot of drag when it's hot. How does it start after about a 15-minute cool down?

There's nothing I can think of about the starter that would have a problem with high charging system voltage. Unless someone has drilled and tapped the crankshaft for a center bolt, you won't find one on a stovebolt six- - - -the balancer is a press fit. Some of the balancers have a 3/4" square hole that a ratchet or a 1/2"-3/4" square drive adapter will fit.
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!