What is the terminal voltage at the battery posts with the engine running? In general, an internal resistor coil is a bad choice. It limits the voltage available during cranking when the battery terminal voltage drops due to the load of the current draw the starter creates. Also, check the voltage downstream of the coil, between the coil and the terminal at the side of the distributor with the engine stopped, ignition on, and the points closed. It should be less than 1/2 volt. It sounds like you've got some dirty or burned points that are limiting the current flow in the coil primary winding.
Jerry

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