Coil Voltage possibly too much?

[Calicat]

Assuming you are using the factory yellow top coil, it is designed for full battery voltage only when cranking the starter. So you are correct that full battery voltage when running is too much and it will overheat. The factory yellow top coil needs to be fed by the factory pink resistor wire (assuming it is intact), or through a ballast resistor if tied direct to battery voltage. Or you can replace the coil with one designed to be powered directly from battery voltage. Lots of discussion on the different options with Pertronix ignition here:

Ignition resistor wire

From my limited understanding, the pink wire on the ignition switch on the steering wheel column is a resistor wire, designed to decrease voltage to the coil after start. So, twelve volts to the coil to start the car, and then less voltage once the key is in the “run” position. This was to protect the points. What would the voltage be at the coil in the run position? Thx