The Pantera has a Ford ignition system in it.
The coil runs on 6 volts and is the yellow top.
When the ignition switch is in the on/run position, there is 12 volts at the power out of the switch BUT it runs into a pink resistance wire that reduces the voltage at the coil ignition terminal to 6 to 9 volts. Theoretically it is supposed to be 6v.
There is another component to this system. The starter solenoid mounted on the fire wall.
It has four terminals on it. The big one is directly from the battery and receives full battery voltage, whatever the level the battery is at at the moment.
The opposite side of that is the #4 gauge wire to the starter field.
There are two other terminals on the solenoid. One is marked S (for start) the other marked I.
When the ignition switch is in the start (momentarily) there is NO voltage to the coil from the ignition switch. The solenoid from the S terminal supplies full 12v (battery) to the coil to start.
So reading your testing procedure, this all makes sense.
You need to get a FORD specific wiring diagram from MSD that clearly shows the Ford starter solenoid in it.
I've had my own runs with those people and came to the conclusion that they were qualified to be classified as total dip-shi ts, took their MSD, threw it over the fence at the neighbor and bought a bolt in Pantera-Electronics ignition.
You can complain that it's much more expensive then the MSD. That's true. It's also true that it works and the MSD doesn't and even EVENTUALLY if you do get it to work, you will discover why it is called the "Might Suddenly Fail" Ignition system?
In order to use their 12 v coil, you are also going to need to replace the resistance wire in the Pantera harness with a 14 g normal resistence wire so that the coil receives 12v from the switch when running. If you don't it will still only get 6v to the coil.
Now it is true that there are those here that are going to swear up and down and rave about the MSD. I can't explain that.
Neither can I explain how I could read a review on ice and snow tires in July, from a guy from Miami, FL, with a hundred miles on his two week old tires that they were fantastic on ice and snow and the best he ever purchased?
Maybe they were on the Zamboni machine at the Miami Ice Rink? Do the roads in Miami ice up on the way to the beach in July? Strange, very strange?
Save yoursel a lot of grief. Get the Pantera-electronics ignition controller from Jon.