Electrical nightmare

I have a 1969 Dodge Dart custom, with a
360 CI motor topped with a Holley 4412 500 CFM carb and a 727 torqueflite trans. My problem is car runs for a short period Of time and then backfires through the exhaust and dies but will refire after a short. time the only thing that I've recently changed it the ignition switch what could the cause of the problem be?