electric choke wiring

There is only one "run" power source into the engine bay and that is the IGN1 "traditional" dark blue wire which feeds the ballast resistor, VR, and any other underhood loads, depending on year. It is NOT fused. It is also the most likely source of OVER charging because of UNDER voltage to the VR, AKA "voltage drop." You might consider cutting the wire, using the firewall end to trigger a relay, and feed the engine bay end off the contacts of the relay. Feed it power from a fuse/ breaker off the starter relay 'big stud.'
CHECK it for drop...........

Turn key to "run" with engine stopped. Measure --one probe at ballast, other probe on battery POS post. You are hoping for a very low reading, the less the better. Anything over .3V (3/10 of one volt) you want to investigate. That voltage reading is ADDED to the set point of the regulator.