I asked the guys at Ignitech https://ignitech.cz/en/ which of their offerings would be a good one for the Savage, and this is the one they recommended: https://ignitech.cz/en/vyrobky/tcip/tcip.htm.
I ordered one and it is on my desk right now:

The price is very reasonable, 175USD, so if it functions there is no longer any reason to hunt for the original Igniter anymore, unless if you are a purist who wants to keep everything original. (if this description fits your profile, shoot me a PM, I have one for sale  )

The staff is easy to communicate with and they take pride in delivering a plug and play solution, which they did.

It plugs right into the harness with the right connector and the bike starts up as it should and it runs like it did with the original ignition module.

As you see, apart from the connector to the harness, it also has a cable protuding with a serial interface connector. this is used to progran the unit.

If you want to purchase one of these modules, be sure to have a way to connect your pc to it, with either a pure serial interface, or the USB to serial. In the latter case you will need a PL2303 Prolific driver installed.
This driver is notoriously tricky, and in my case, I could not get it to work on my trusty WIN7 machine, but on the WIN11 laptop it worked well.

If one of these 2 ascessories are chosen, then the advance curves are dublicated relative to 10 different positions on these sensors, and curves with less advance can be programmed to take effect at or approaching to WOT.
You can modify the advance curves by pulling the dots on them, or by displaying them as a table, and edit the numbers depending on your temperament.

But it is best to try that yourself, and then we can talk about issues.

My problem is that I don't myself see a need to retard but I like the programmability and a nice toy it sure is.

The module arrived preprogrammed to fit the bike as it came, plug and play as advertised. These guys really know their stuff.

Wow Finn, pretty cool.  Thanks for sharing this.  

However, as it goes with all things involving a computer, I have zero understanding of how to set this contraption up.  The website doesn't provide much info.  I am probably missing the cues.  Us old-school nuts & bolts folks can get lost in the world of bytes.

What exactly is a "PL2303 Prolific Driver" and where do you get one?  I assume it is some sort of application or program.  Would I have to purchase that and then download to my computer?  I have very bad luck with that sort of stuff.  By the time I'm finished I have usually screwed up my laptop.  What does the prolific driver do?  I have a Win11 system.  Could I avoid the prolific driver?

It sounds like you have actually installed the ignition system.  Do I have that correct?  Did you install the ignition system and did the motorcycle start up and run?

The curves you posted show full advance at 6000 rpm.  Is that where you have it set, or did you somehow adjust the curve to reach full advance at 4000 rpm?

You mention timing retard via a vacuum switch or manifold pressure sensor.  Our big single develops very low manifold vacuum.  Is there a range of operation for the switch/sensor?  Under normal conditions, our big thumper may not develop sufficient vacuum to maintain full advance, it might run continuously with the timing retarded since the engine develops such little vacuum at part throttle.  Do you have any info on the switch/sensor?  Is it a MAP sensor?

Do you know anything about the rev limiter?  Is it a soft limiter?

I see they have some CDI units specifically for single cylinder engines.  Is the unit you purchased a TCI system and is it specifically for a single cylinder, or is it a CDI system?  If it's not a CDI system, is it a multi-cylinder TCI unit adapted to a single-cylinder application?  Do you happen to know if their CDI units are setup with a PC or do they use DIP switches?  A DIP setup might be more user friendly for a guy like me.

I marked up your picture.  Is the connector that I have a green arrow pointing to a direct fit for the connector plug on the motorcycle's wiring harness?  If so, how did they know what your plug looked like and which wires go to which pins?

Is the connector I have the yellow arrow pointing to a direct fit for your timing pickup plug?

I now see that you got a 4-cylinder unit, and I suspect you are only using half of the system.  So, you end up with a waste spark on the exhaust stroke, just like the stock system.  One nice feature is you kind of get two ignition systems.  You have a spare system.  Of course, that assumes that any sort of failure doesn't occur with a component that is shared.

If you got this thing running, you are an absolute wizard.  My compliments.  I see in their description that they custom make the module with a plug that is compatible with your existing motorcycle harness.  That's certainly a nice feature.

Sorry for all the questions.  I just can't help going back through the literature.  Very interesting.  Please tell us more.