[Laird Scooby]

It looks like a very early (contact assisted) electronic ignition unit. In the early 70s (and in fact later) many of the hobby electronics magazines of the time (Elektor, Practical Electronics, Everyday Electronics and similar) produced circuits for contact assisted electronic ignition units, some also had bespoke PCBs made and also bespoke heatsinks made - these were sold at cost + a small percentage to readers wishing to build their own that used what was already tried and tested and/or didn't have the facilities to make their own.

If you can figure out the connections that make it work then try it and if it still works, all good. If not, revert to standard and sympathetically remove it.

Another thought that crosses my mind is it could be an early cruise control servo - the "HT" connector could in fact be the Bowden cable entry point - unexpected extras on the throttle linkage will add evidence to this theory.