Not sure where to post, car won't start with brake pedal pressed

^^ OK here is the deal. ^^

The original ignition switch wiring is something you MUST understand and it is not complicated.

Look at the diagram of the ignition switch I posted above. You are interested in J2A, Dark BLue, and J3, Brown.

These are the ONLY wires going through the bulkhead connector from the switch, that are to be used for ignition. The DARK BLUE is the "run" circuit and is powered ONLY in the key "run" position. THIS GOES DEAD during cranking

During cranking the BROWN supplies power. This wire originally went to the coil+ side of the ballast resistor

IF YOU HAVE an MSD you must chase both these down at the bulkhead connector, make certain the dark blue remains connected to run such things as the VR and alternator field. Jumper the BROWN into that and run that off to your MSD "small red." If the ballast resistor wiring is intact, and the original coil+ wire is as well, you can just bypass the resistor and use the old coil+ wire to the MSD "small red." This wire is sort of a "trigger" wire to power on the MSD

Then the big black on the MSD must go to a good ground, and the big RED must go straight to a good battery connection, such as the starter relay "big stud."

MAKE CERTAIN that ONLY the wires from the MSD ARE THE ONLY wires hooked to your coil. DO NOT connect a tach, a radio capacitor, or anything else to the coil