Nicely made frame, from outward appearances. The semi-wrap seatstay tops are a bit generic but nicely pulled-off. The Prugnat lugs and Cinelli shell mostly rule out Japanese, right? I mean other than a few small custom shops, Japanese OEMs had a strong incentive to use Japanese lugs and other bits. Those lugs and seatstay tops were so common on high-end frames that it doesn't help at all to point to a builder, but I still like 'em. Anything with a Cinelli shell is bound to be high-end because those shells were always expensive.

I forget when Portacatena holes started disappearing, thinking '82-ish? Of course, even after <C> stopped making them, they were still in the distribution pipeline and builders' dropout drawers, so they went away gradually (I still have some!). Someone here knows the earliest possible date for a Portacatena but I wanna say '78-ish. Ah yes, Chuck Schmidt's Campy timeline says they were first shown at a bike show in late '77, so '78 model year would be the first to show up on bikes for sale.