Starting Issues 1971 Dodge Dart Swinger 318

This may sound crazy but have you checked out your ignition switch to ensure that you are getting voltage out on the Ignition 2 circuit. The switch for my 68 Barracuda is not hot on Ignition 1 when the engine is cranking. If you are checking voltage with the switch in the run position, you can have juice going to the ignition system but not have any while cranking if Ignition 2 side is bad.