Help ignition..here we go again,,,

Same ol 360 ..milled the block to even it out..same with the j heads small valves basically stock pistons and 340 cam.,edelbrock carb and manifold...in a 73 duster with a 74 wire harness,stock ign and charging system..everything new or rebuilt..orange box ign... mopar regulator..what in the system would keep it from starting while cranking but let it start just as the switch comes back to the run position...j