I'm going to overlook your distributor choice. That's up to you. Others here may have suggestions about that question.
However to change from points to HEI you need:
12 volts to your distributor all the time---and this is very important. Remove the ballast resistor or any resistance wire that might be in your wiring harness. We don't know what you have since around 1971 GM started using resistance wire instead of an inline ballast resistor and if you buy a new wiring harness you might have either resistance wire or you might have an inline resistor. Points distributors use 12 volts when cranking but run at 9.3~9.5v. A constant 12v would burn points up. Your HEI won't work at the lower voltage.
Add (or make certain you have) a good 12 gauge wire from your ignition switch to your coil or to the Bat terminal in the distributor cap.
Here is a tip from personal experience. If your ignition switch is not stout enough to handle the current draw (at startup) of the HEI distributor, don't flirt with trouble. Some ignition switches will just flat burn out if subjected to the increased current. Ask me how I learned this would happen. If you're not certain, feel free to add an inexpensive Bosch-style relay between the 12 ga wire (coming from the positive terminal of your battery or the starter) and the bat terminal of your distributor cap or your coil (if the coil is separate from the distributor). Then use the ignition switch to activate the relay. I promise you'll never burn out an ignition switch by doing this and a new ignition switch will cost more than that Bosch-style relay.
Now, install HEI coil and plug wires, plugs for the HEI and gap them correctly---.40 to .45inch
That's about all that comes to mind. Good luck.
