Have Kugelfischer on Flavia 2000 - which needed a new fuel pump and rebuilding. Getting all the info was complicated (many sources required) but ultimately successful. The KF system works quite well, gives clean solid power up to redline. Cruises happily at 80, wants to go 90. Its very quiet and smooth 40-65.
Starting is really the only downside - cold starting (<40º) is quite lumpy, as the oil in the pump is cold and takes some time to warm up - ten minutes its fine. Hot starting is a bit of an issue as the enriching device is not readily available, so we hooked up a manual disconnect, which is used when engine is super warm (summer) and needs a quick restart. Works like a charm.
The Flavia is a seductive charmer, loves to run and go all day without fatigue. Very sophisticated and easy to live with. A different ethos than the 1950s golden era cars, but its nice to imagine being an Italian gentleman of the era.