Diagnosing high voltage

"Follow the path." And start over as if it is a new problem. Functional path is key--through harness---to junction in engine bay---to VR "blue" (ign) terminal. Through guts of VR to ground

Second path is key--harness--blue--to VR field--through field--out on green--back to VR and to ground through VR

1...Disconnect the green from alternator, make sure it does NOT charge. If that is true, take a alligator lead and ground the field that was connected to the green. Make sure it charges and it will OVER charge. Reconnect green

2....Disconnect VR connector. Run and make sure it does NOT charge. If not, make sure VR is grounded. REALLY grounded
RE check voltage as close to VR as you can get. IT MIGHT BE time to find a pin/ needle to puncture into the VR blue wire terminal at the VR with it all connected up. RE-measure V drop between VR blue terminal and battery plus. If this is OK,

Check as well as you can that VR connector is in good condition. If so, replace VR

If there is ANY doubt as to condition of VR connector, last I knew NAPA had these

It should also be possible to "jerry rig" VR to sorta test connector condition. Connect an alligator lead to VR blue terminal at VR ("top" terminal) Jumper this over to a battery source

Clip second alligator lead to "side" terminal of VR (where green connects) and run that over and connect to the terminal on the alternator where the "green" normally sits. This should eliminate any harness drop or poor connections for testing and prove, at least, that the VR works properly. Again, make CERTAIN VR is GROUNDED