Voltage problems, cutting out when hot

The 5.90 and the 10.19 volt are measurements taken from either side of the MSD .8ohm ballast with the key in the on position, engine not running.
The two pictures that follow are being taken from the 5.0ohm side of the factory 4 pin ballast in the same manner, key on engine off.
And yes, one of my main concerns is in fact why (or where/what) is the VR getting the wrong information...
Thank you for the well laid out explanation and graphs.
A '72 has two big differences from a 60's type scheme shown above.
Voltage regulator.
Controls the rotor's connection to ground (green wire) based on voltage in the blue wire. Think of the blue wire as a voltage sensing wire. No appreciable current flows into the VR from the blue wire.
Ignition Switch
Additional connector for all the wires to and from the switch because its in the steering column.
ECU ?
Some '72 cars may have had a Chrysler ECU, but I'm assuming here that the ECU wiring was added. A factory ECU from the time would have two resistors and 5 wires.
The power for the ECU can be tapped from any location on the run circuit. In the below illustration its shown as a splice.

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