Try pouring a little gas down the center carbuerator. does it run for a couple seconds?
Next try timing... 1-5-3-6-2-4 you may need to move the dizzy to optimize timing.
You mention HEI distributer. Are you still using the ignition resistor? If you are, try bypassing the resistor.
You have a multi carbs, and a new ignition. Chances are the problem is in one or the other, but it can be in both.
