Well lads, I finally gave in and converted the swingarm to electronic ignition and 12V
Must say, quite happy with it
Without any other adjustment, it became a reliable first kick starter. Even half hearted kicks get it going now.
Before, it had a flat spot when opening the throttle to quickly, but that's no longer there
I also find the bike less vibrating, and turning more regular now, although this might relate to my painstaking timing adjustment.
Installing it was very straightforward. I put the black box under the tank in the triangle formed by the main tubes coming from the headstock, and bolted the twin coil to the tank strap. The electrical connections are all in the headlamp cowl (gets a bit crammed in there now).
For the ignition switch, I drilled a hole in the headlamp cowl, and also connected the light switch to it so if I forget to turn the lights off, I won't be left with a flat battery. Had a bit of luck there, because if I had drilled the hole 3 or 4 mm higher, the connectors would have touched the speedometer.