Cranks but won't start. Unplug ground at field spade on Alternator and it starts?

340sFastback said

This was the voltage regulator that had been on there for 20 years that died 3 weeks back and was replaced by the mechanical one from Napa:

Advance Auto Parts - Down for Maintenance

The local parts store says they can have one this afternoon.

Click to expand...

The NAPA VR32 has resistor's underneath? If you open it you'll see points. Very simple system.

I'm the last guy to tell you to buy parts and swap as a diagnoses method.
Have you tried starting with the VR ign side connected and the field terminal disconnected?
If it doesn't start then, that would seem to pin it on somethig to do with the VR.