No thanks

The running on when you shut it off is not related to timing or ignition, there is no ignition when it is shut off.

Running on or dieseling is normally caused by the throttle blades being open too far allowing enough air / fuel into the engine that it diesels.

This is usually due to not enough initial timing so the idle speed (not to be confused with idle mixture) screw is turned in too far to compensate. This results in the car idling on the primary circuit, not the idle circuit.

Timing is locked.... do you have a vacuum advance on it?
Do you have holes drilled in the butterflies?
Any other vacuum leaks?
If you look down the throat of the carb when it is idling do you see fuel dribbling or otherwise being pulled through the main venturi?