There is nothing particularly mysterious about "HEI" (High Energy Ignition). It's simply an ignition coil capable of producing open circuit voltage above 50 KV- - - - -far above what a conventional point type ignition system can develop due to the limited current capacity of conventional ignition points. The 50 KV capacity was mandated by the "Clean Air Act" of 1968- - - -which required engines to go "emissions legal" for at least 50 K miles without the ignition or fuel systems being serviced. That problem is solved by using a high primary current coil triggered by solid state electronics instead of points. Since clean, properly gapped spark plugs usually fire reliably at less than 10 KV, "HEI" is really just for people who are too lazy to do regular tuneups. Even full throttle acceleration requires less than 20 KV at the spark plugs.

If you're planning on running the original 6V electrical system, your options are going to be VERY limited when trying to use electronic ignition.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!