The main reason for a resistor is not to prevent the coil from overheating, it is to reduce the current to a level that contact points handle.

Be careful. Some electronic distributors can not handle the amperage of a 12V coil. The first 3 years of Datsun electronic ignition could not, and so used a resistor. Older pertronix cannot handle it, but newer Pertronix (I'm told) can do it.