Voltage to coil

The above is correct, and if you are trying to start the car by jumpering the start relay or the starter solenoid, that bypass circuit does not get engages.

The "bypass" voltage, on the brown, going to the coil side of the ballast, is the bypass coming from the ignition switch through the bulkhead.

I would also check out the path for the "ignition run" (dark blue, also known as "ignition 1") You say it is 11.6. WHAT IS the battery voltage?

Do this:

With key in "run" engine off, and make sure points are closed---look for a low reading at coil as opposed to "same as battery."

Now with the points closed, put one meter probe on the battery and the other on the key side of the ballast.

You should have no more than 1/2 volt, and that is generous. Less is better.

The other thing a voltage drop causes at the ignition switch side of the ballast is OVERCHARGING, because this is the supply and "sense" for the regulator. If this voltage is dropped through the harness/ bulkhead from the battery, the regulator simply ramps up the alternator to compensate.

Before I (just got it running) rewired my 67, there was a ONE VOLT drop through the bulkhead/ harness. The system was charging at more than 15 volts