- "I checked the voltage to the coil with the ignition on and it's a steady 6.5 volts. At run, it is a steady 14 volts. Same at the battery."
- Big problem right there. With engine running, the voltage to the points should be about what you have when you simply turn the ignition on (no engine running), 6.5-7 volts. When you turn the ignition to "Start," that is when you should have 12 volt battery voltage only to supply the coil with a good hot "kick" to fire up the engine and when you snap the key back to "Run," the resistor wire takes over to drop the voltage down to 6.5-7 volts so the points do not burn out. 14 volts to the coil with the engine running means you have an electrical problem that is providing too much voltage.
If you, or someone else, has ever done an upgrade to electronic ignition, these typically require 12 volts to work and the resistor wire going to the coil is either removed & replaced, or a wire is re-routed to the coil drawing from a known 12volt source.
So first you want to look into the wire (s) going to the coil of which you should have 2 of them, the 12volt sourced wire when starting the engine and the resistor wire that the engine uses to run on so you do not burn your points. It sounds like the resistor wire is in place and working seeing you have 6.5 volts with the key in the "On/Run" position with the engine off. You need to figure out why 14 volts with the engine running.
Make sure that no one has wrongly wired up an additional wire from your starter to the coil. You should only have a "purple" colored wire going to the "S" terminal on the solenoid that activates the starter to spin when you hit the ignition switch to start your engine.
Next would be your ignition switch. These go bad. It is possible that something has been switched or jumped on the back side where the connector plugs in OR there is a short internally in the switch itself.
You will want a wiring diagram to trace wires and test them to isolate your wiring problem.