Of all the posts, I'm going to pick on yours Big_John. First, I agree the aftermarket stuff without ready parts availability is crap... buy on EB and then try to make it work when it fails (often too soon). The GM based system you linked to would be a nice piece for someone who has extensively modified their engine. GM started 12v coils in their HEI in 1974 and some applications had .045 and .060 plug gaps as a result (refer to the link in Big_John's post). The reason I would not recommend this as long as acceptable parts are available for the stock Chrysler Electronic Ignition is the 6volt coil and ballast setup should start and run fine with a compatible spark plug to the original. This system did not increase the amount of energy so much as reduce the maintenance of points.
For anyone seriously considering the change, the 12v coil systems will increase spark energy... I know this sounds nice, but with more energy, you will need to fiddle with spark plug gaps and heat ranges until you find something that truly works. This is problematic for a stockish engine as you can increase the temperature of the plug enough to cause detonation/preignition problems. If you bumped your compression, you are already in that situation... but if your build is close enough to a factory configuration that was once available, you could stay Chrysler 6v and use a plug from the application that matches your build (more or less).
If you still have to do this, I would choose a plug brand that has several heat ranges available in the correct size and seat for your cylinder heads and buy a variety... Build your GM ignition, and tune your plugs, start with a .045 gap and the coldest plug and work your way warmer until you no longer foul them... In a street setup, you don't want to get anything close to too hot or Murphy's law will take over.
If optimizing spark plugs sounds easy, great... it is, But it's constant fiddling for a racer that makes maintaining points seem like low maintenance. I personally wouldn't pooh-pooh a Chrysler electronic conversion... but anything else is really for the guy who wants to wrench on their car a lot... or fool themselves into believing they have made an improvement with no negative side effects.
A few more things to consider... different brands of plugs may have different resistance values and heat range, even though the book tells you they are the same. There is much more to tuning an ignition than I covered... I'm only focused on why I wouldn't recommend any 12v ignition replacements. If I was so inclined, I like the link Big_John posted, but only do this if you really want to forever be trying to tune away glitches in operation. I feel the same about all "improved" ignitions... so it really doesn't matter what brand you prefer.
There are others here with much more knowledge and experience than I when it comes to racing type modifications, but if all you intend to do is cruise reliably... any deviation from stock will have a negative side to it.