charging system issues

Voltmeter? You don't have one unless your replaced the ammeter.

However...........

The most probable causes of overcharging............

1....poorly grounded regulator. Scrape the firewall and regulator flange clean and use star lock washers. Better, run a no10 wire direct from battery (or engine block) to one of the regulator mounting bolts

2....bad regulator or poor connection in the regulator connector

3....problem in the brush holder of the alternator. One field terminal (blue) goes to switched 12V ignition power. The second field terminal (green) goes back to regulator which controls "the amount of ground" so to speak. IF THAT BRUSH holder is shorted to ground ....and can be part of the time..... the alternator will charge full output