Tune up Questions

My understanding is that if you have an early slant with a removable aluminum tube around each spark plug, you remove the metal gasket on the spark plug. If you have a later slant head with the recess as part of the casting, leave the gasket on. I forgot the number (Champion R12K or such?), I just look it up in the book at auto parts. Some people get a different heat range (14K or such). Search posts by SlantSixDan. I would set the gap for whatever the 73 manual spec'ed for electronic ignition, but you could try more. If too wide, you will get misfire at high throttle, low rpm, like climbing a hill or entering a freeway.

I think the 1.5 ohm of your Summit coil indicates a special "electronic ignition coil", since the factory points coil has ~0.6 ohm resistance as I recall. Yours likely has an internal resistance that serves as a ballast resistor, but maybe just a "half ballast", requiring an external ballast to finish the job. I would bypass your factory ballast (coil side if a dual ballast) and use the ballast on the side of the coil, since they probably match. A wild guess is that the intent is to use the ballast on the side for normal driving and bypass it for racing. In the later case, your coil and module will eventually get hot.

I think silicone plug wires are best, and good for electronic ignition. I got a set w/ cap & rotor for my slant cheap (~$18, UEI I recall) via rockauto.

Maybe too late for you, but for others, I suggest the HEI module upgrade. You can forget ballasts and use a better E-core coil. I think the GM 8-pin module and coil is simplest and best.