HEI Problems

Without a link to what you are talking about I can only guess, but this:

Many perhaps MOST of these girls suffer from voltage drop in the circuit path from the battery........bulkhead........ammeter circuit........through the ignition switch.......back out the bulkhead..........to the ignition VR/ alternator field "run" power

THIS VOLTAGE DROP actually causes the VR to OVER charge the battery (over voltage). Whatever drop is in that path is ADDED to the VR set point

I've written about this hundreds of times on this board, here is what you do:

With the engine stopped, turn the key to "run"

Stab one probe of your meter into the battery positive post. Connect the remaining probe "as close as you can get" (electrically) to the VR ignition terminal........the terminal that is supplied from the blue "run" wire.

What you are hoping for is a VERY low reading, less than .3V (3/10 of one volt) Any/ much over that you need to find the cause

Cutting that blue feed wire, using the bulkhead end to trigger a relay, and then feeding the output of the relay to the cut end in the engine bay would relieve that drop, as the relay power would come from say, the big stud on the start relay.