Now I deliberately left the cables a bit long for the box, to be able to move the box around as I like, but the position under the seat didn't make me very happy as I noticed that the seat was pressing on the top of the box.
Take out some ally sheet (totally not an old street sign), trace a stock ignition box and this will ultimately form the new baseplate for the ignition box to go under the tank.
... and then the box basically does what you expect from it:
Except it doesn't start quite so well. After a bit of probing with the wideband it became rather apparent that the curves are different: It uses less ignition advance down low (good, because I had some detonation issues, when opening the throttle on a REALLY hot engine) and quite a bit more on the top. (Also good, because I know this engine still leaves some on the table, as its top speed is lower than the old worn out engine with an Ignitech installed!) Both of which would require quite a bit of rejetting to get it to work (same as I observed when going from the stock box to Ignitech many, many years ago) and my car not being usable, the standard box went back in, because it fires up instantly and works well (enough) for a daily at the moment.
The other two thing that needed tackling, where that the silicone sleeve on one of the three wires coming out of the alternator had split and the second, ever since I put on this Guzzi-tail-light I had problems with a flickering (and regularly failing) light.
Once and for all fix: drilled a small hole through each brass contact strip and soldered it directly onto the bulb. Job done - sometimes you do actually have to solve electrical issues with the big hammer.
I am currently a bit hesitant to make major changes to my TR1, but I have received my new Ignitech and I will at least make a new mounting plate and prepare everything so it can go in and I will probably also go ahead and re-adjust the carbs to work with the Gen2 box at some point, so I can swap over to that as the actually IC-based timing calculation is a notable step forward compared to the analogue setup of the tinbox TCI that was installed stock.