New to the Mopar scene.. got 68' cuda need help.. new motor...

Welcome to the forums Kingofthehill. Mopar Electronic ignition is designed to work with a ballast resistor, this preserves the coil at idle, good for street motors. It may be possible that your distributor is set with full manual curve and that is why the vacuum advance is plugged. I would think you have a timing issue. Have you checked the spark plugs?