Well I'll be gob-smacked! I didn't look closely at that shot of the underside of your BB shell, now that I do I see it's stamped +GF+, and yes that IS a Georg Fischer...don't know why I assumed it was not, but it doesn't look exactly like the GF shell on my '75 Allegro, so I just assumed. Wrong.
Anyhow, it's sand-cast and a well-respected make, but doesn't necessarily mean a Swiss manufacturer made the frame, since Fischer shells were used in several countries (obviously by Cinelli in Italy for one, as you have found).
The other little detail that reminded me of "Swiss" is how the stay tips (where joined to the DOs) are pointed. This was something I've seen on several Swiss frames, but it's a pretty weak clue to hang anything on.
The 818 (if you're thinking 1981) doesn't jibe with what I think is the likely age of this frame: the long Campay DOs, the nutted brakes and cable routing/bits all are more "'70s" than '81...but one question: do those Shimano 600 shifters use the unique Shimano boss (round with a rectangular "tab") or are they conventional square?
Last edited by unworthy1; 06-10-12 at 10:03 AM.