Positive coil wire

J2B going to the coil is fine for turning the MSD on/off. Disconnect it from the coil of course.
But power to it goes through the ballast resistor when the key is in run.
So it is not OK for supplying the voltage regulator.
The voltage regulator needs to be connected to the ignition run circuit on the other side of the ballast resistor. J2 and J2A.
I was going to eliminate the wires I'm not using the blue positive coil wire was gonna be one of them, I'm not running a ballast resistor being that I have a msd box. If I can use that wire as a key on ignition for the msd and voltage regulator then I'll use it. If not what wire would you suggest to use? I've had this msd box wired up to a different vehicle I understand how it goes, just not familiar with the a body wiring and what would be a good key on ignition source to use.