There's no single "point gap" for a 1968 Ford Mustang. The correct point gap depends entirely on the specific ignition system and distributor used in that particular Mustang. Different engines (6-cylinder, small-block V8, big-block V8) and even different versions within those engine families had varying specifications.
To find the correct point gap, you must consult your owner's manual or a reputable repair manual specific to your Mustang's engine. The information will be in the ignition system section.
