I used a 4 terminal switch and wired the MSD power wire to the switched side of the terminal. Kills the ignition immediately.
That would probably pass tech almost anywhere but if I understand what you described correctly, what do you do about other critical components, like an electric fuel pump if you have one. If you need everything shut off in an emergency, especially if you can't, you might have a real bad situation on your hands.
Engine shuts off alternator doesn't charge, fuel pump shuts off when when voltage is not present to energize the relay
Gus
64 Plymouth Savoy 493 Indy EZ's by Nick at Compu-Flow 5-Speed Richmond faceplate Liberty box Dana 60
fuel pump shuts off when when voltage is not present to energize the relay 
