Pull the distributor cap off and take a peek. In '72 pretty sure it would have shipped with points & condenser. Many have been replaced by now with solid state modules like the Ignitor by Pertronix.

Having any luck?

Yes, everything will work great. Make sure the distributor itself has a good ground. It grounds itself through the housing to the block. Make sure there's no paint at the mating surface for example to interfere. There's a flexible copper wire on the breaker plate too, if it's looking long in the tooth, replace it. You'll want to leave the ballast installed - the points won't handle more than 3 amps or so, period.

In theory, if you install a different coil without increasing the primary voltage (by removing the ballast resistor) the voltage at the plugs won't really change. Plug firing voltage is drawn not applied. It takes what it needs. Higher compression, higher loads, leaner fuel mixtures, worn plugs etc increase the firing voltage required.

Normally at idle about 8,000 volts to fire a plug or somesuch. That leaves about 10,000 volts in reserve with a stock coil. Installing a 40,000 volt coil doesn't change the voltage required to fire the plugs. It does have a higher reserve voltage if necessary though.

You can open the plug gap a little if you like. I would wait till the points get replaced with the module, and the resistor wire is bypassed. This higher primary voltage does puts the secondary or high tension part of the ignition system under more strain as the secondary voltage output will increase, consequently the coil will run hotter, also the rotor inside the distributor will burn faster. The bigger the air gap between the rotor and terminal, and the larger the plug gap, the higher the secondary voltage builds up in the coil before it fires. When GM developed HEI they initially had a plug gap of .060" or so, and it caused everything to burn up.

If this secondary voltage gets too high in a point distributor it will likely arc to ground someplace easier than the plug gap, or crossfire between wires, or inside the cap, or even outside the cap.

Start out with factory spec heat range plugs and factory gap and see how it runs. Then, open up the gap later maybe. Make sure the carburetor mixture and jetting is correct before (maybe) stepping down a heat range. If the plugs are burning too rich, the carb needs adjusting - before changing plug heat range. One thing at a time. It's tedious, but with ignition and carb tuning especially it's important. It you change a gazillion things at the same time it confuses tuning.

Not to get off track necessarily, but do you have any YT videos of your engine Ultraranger, where we can see/hear it making some music? Sure looks nice, your attention to detail and everything.

Thanks ND! I don't speak inline 6 very well. Coil ohms? 4 and 6 cylinder engines may sometimes use a 3 ohm coil? There's no spec for a different coil in '64 FWIW. Keep in mind, you can use just about any combination of parts you want provided the total primary ignition circuit resistance doesn't exceed the current carrying capacity of the device you're using. Points will fry at about 3 amps. Use Ohms Law to determine this.