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

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

Thanks for the additional info. Now we all know what is on the car.
Sorry but at least I missed this part when I was responding the other night.

340sFastback said
I do have Unilite distributor been on there for 14 years and it gets power for Ignition 1 side of ballast resistor. Unilite igntion module and MSD High Vibration coil mounted in stock bracket on manifold.

Dana67Dart said
That proves the IGN 2 is not providing battery voltage to the coil plus during cranking.

Why is the big question.

That's what I would have first suspected - ign 1 & 2 wires might be switched

340sFastback said
Ballast is .8 ohms

Correct for points. Not sure what MSD coil and Unilite will work best with for street use.

340sFastback said
then put key in start position I measure 12.3 volts vs the battery 12.5 volts.

With points, the voltage drop from resistance in the line will only occur when the points are closed. And once its saturated the current will reduce. When the points are open there is no current flow through the coil, and with no flow, there is no resistance. So with no flow voltage is the same everywhere.