Ignition won't crank engine unless ballast is unkooked

...74 360 4speed duster...

Real 360 Duster or Duster with a 360 swapped into it? Original 4 speed car?

Something else to think about is the clutch switch. It's what supplies the ground for the starter relay to power the starter solenoid. On the factory cars (that haven't been modified), you have to have the clutch in to start the car.