distributor

If you want to use the HEI to trigger MSD, connect white MSD trigger wire to black HEI wire that would have went to coil negative. Red HEI goes to 12V ignition, that comes from IGN1,IGN2 connecter together by bypassing ballast. Ignition coil hooks to MSD.

Follow MSD instructions, similar to using pertronix, or Mallory Unilite.