Glowing Coil Terminal

That is WAY too much drop. Unhook the choke and see what it does. "That point" in your electrical system not only also powers the VR, it ALSO is the "voltage sense." Whatever that is in voltage, below battery, the VR ADDS that.

This means that if the VR is regulating at 14, that plus the .5 will end up with 14.5 at the battery.

One way around this is to chop the blue wire between the bulkhead and the resistor, and put a bosch type relay in there "electrically." You can pull fused power off the starter relay 'big stud" fused with say, a 20A inline fuse, and use the "output" of the relay to power the blue wire going to the resistor. This should stop the drop problem

There's many ways to skin this cat. You have to realize that these cars were not built with additions and modifications in mind. They were pretty minimal when produced.