Headlight Switch Cranks Engine??

Gary. You definately want to find where the resistance is. That's bad for the battery and bad for lights.
15.5 is too high.
Yea the bulkhead connector is often a problem.
On my '67 I've found the ignition wire from the bulkhead to the regulator had a 1/2 Volt drop. The terminal crimp at the ballast resistor connection wasn't good. so you never know. Measure ffor that voltage drop back backprobing while running and take of it. :elmer: