Electronic Ignition

If you already have the 6V coils with the ballast resistor then you are good to go with a simple EI as you dump the ballast and connect the two 6V coils in series not parallel, you only need to change the coils with some of the digital ones or the CDI based ones.

As to which is the easiest that depends, I am used to Boyer MK4 but Pazon Sure-fire and Wassells will not be much different and all use the 6V coils on a twin,

I dare say a number of contributors will soon be along to air their experiences/prejudices, but in the meantime try searching the forums for something like "Commando electronic ignition". The most recent discussion seems to be here: https://www.nortonownersclub.org/node/12491

For what it's worth my experiences are:

1. In the mid-70s I found the contemporary Boyer system a notable improvement on the standard points on my '71 Fastback: steadier tick-over at a lower speed, presumably thanks to greater advance/retard range
2. On my current '72 Combat Fastback the points it came with worked absolutely perfectly. However, since I had a Pazon system in stock I fitted that when I had the timing cover off to check the cam-chain adjustment. Once again the extra range allows for a better tick-over (but perhaps a less notable improvement than that which I remember from the '70s).

And of course there are the attractions of simplified wiring, elimination of need to check/adjust points, and no worry about wear in mechanical advance/retard.

If you are starting from scratch i.e. not replacing existing electronic ignition, then the easiest to fit is the Tri Spark Classic Twin as there is no separate 'black box' - everything fits within the points cover. I have used Tri Spark systems on previous bikes and was pleased with the results. It's not the cheapest but it works very well. You can retain the existing 6v coils. It has an anti-kickback feature which works a treat and helps to avoid sore ankles etc.

...have to remove the tank to get decent access to the coils, and to remove the resistor and condensers. Also the need to clarify the ignition wiring to coils and ignition.

I've used Tri-Spark on two Commandos and for ease of fitting and just as important setting the timing they are simple. On both occasions the Tri-Spark replaced aging Boyer systems which were causing issues. The Tri-Spark also has an 'anti-kickback' function incorporated.

As previously 

(Submitted by Brian Roche on Wed, 05/10/2022 - Tri Spark).

Just upgraded from Lucas Rita (1984 build) to my 1977 Mk 3.

It was good before but it’s better now - smoother power delivery - no more flat spots - mirrors do not vibrate as much. 
The bike ran well before but the new Tri Spark unit has transformed the performance.

it sounds better - runs better etc.

Glad I upgraded to newer kit!