Bypassing ballast resistor
yep, thats the distributor I'm using. I don't have a brown wire with a loop though. None of my wires are the same color. But I think I get it now, I need to attach the power wire to the positive coil wire and the rest are unused and can be removed along with the ignition ecu.
Two of your ballast wires are powered (one in the start position and one in the run position)
Connect them together and power your new distributor off that, or it will only run in one or the other (start or run)
Using a test light it is easy to determine.
Unplug all the wires from the ballast.
Turn your ignition on and test the wires till you find a powered wire (that is the run position wire)
connect your tester to the other wire and turn the key to the crank position.
When you get a light in the crank position, you found the "Start" wire.
Connect those two together and power your new coil with it.
This how my HEI kits hook up also, so I know it works this way.
My car is a 73 also, and had the exact setup yours has until I installed the HEI.
I cut those two wires all the way back to the harness, connected them together and ran a new wire from the harness to the new coil.
Then cut all the original coil wire out.
Same with the factory module wires (I cut the wires off right at the factory harness and taped it all back up)
Hope this helps