'68 barracuda ignition switch power on issue

You have two switched ignition wires. Ign 1 is blue, Ign 2 is brown. Ign 1 has power in run position and feeds power to the coil thru the ballast resistor. Ign 2 has power during cranking and feeds the coil a full 12 volts for starting, bypasses ballast resistor.
If your running an MSD you want to splice Ign 1&2 together to feed the MSD box switched ignition input lead. Doing so provides power during crank and run.
Which ignition terminal is the best 12 volt key source to give MSD box 12 volts in run and start positions?
Ty