Overcharging

The very high voltage means you have something causing the alternator to seriously overcharge what is sometimes called 'full field." Meaning the field is somehow getting full battery current. What I'd do:

Check carefully that the VR is well grounded. Remove it, clean around the firewall bolt holes, the backside and front of the VR around the holes, and remount with star lock washers.

Work the VR connector in/ out several times. Check the wiring, especially the green VR wire that it is not pinched somewhere. If that wire becomes shorted to ground, this problelm will occur

Also Check the alternator brushes that they are NOT grounded to the case. Remove and inspect the alternator brushes. Make sure there is no evidence that the insulators/ mounts are allowing the brushes to ground.

Last, this could STILL be a problem in the supply voltage to the VR. "Up to a point" the lower the supply voltage to the VR, the higher the battery voltage will charge. This, again, is because the VR power/ sensing terminal "thinks" the battery is low and ramps up the field current in an attempt to compensate

See if you can "catch" this problem at home. Monitor battery voltage and bring up RPM to show that it is coming up too much. Then swtich your meter to the ballast power terminal and monitor that. If the ballast is showing "normal" 14V charging voltage, and the battery runs high, the VR has voltage drop between it and the battery, in the harness