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 before it goes through the ballast resistor. J2 and J2A.