My first mopar "stranded" moment with the HEI setup

If you wanted to be Space age you could run a TEC between your HEI and a heat sink. Something like this:

TEC1-12706 Thermoelectric Peltier Cooler (12V, 60W) - ElectroDragon

With the thermal stuff I've dealt with at work air flow is key. Some of my rules of thumb are (I'm far from an expert but have real world experience):
-No thermal conduction going down, remember heat rises. Place your thermal conductor above or vertical. This allows for natural convection.
-Fans help if done correctly. They need a correctly sized intake and exhaust just like an engine. (I got a fun work story on that one)
-Flatness and surface roughness is key to excellent thermal conduction, this is where the thermal past can help if used correctly.
-Use quality materials, copper, aluminum or Diamond if you have some sitting around.
-Avoid barriers like anodization, paint, grease, goo-goo,and boogers. Acceptation is thermal compound.

A good read is Hot Air Rises and Heat Sinks: Everything You Know About Cooling Electronics Is Wrong

Hot Air Rises and Heat Sinks: Everything You Know About Cooling Electronics Is Wrong: Tony Kordyban: 9780791800744: Amazon.com: Books

This is a great book written by a Thermodynamic engineer throughout his career. Its explains in layman terms and is quite funny. Its not a boring engineering nerd book.

Now that my nerd hat if off it seems a lot of electronic ignition modules from Ford to GM are not well made anymore. On my Ford side people who still have Duraspark swear by Motorcraft only or like us, buy two department store ones and pray the second one gets you too the store or home or swap to HEI so you can at least guarantee the store will have one..