What frame(set) am I looking for? (Outside of my narrow Columbus world)

All great answers. And I learned some new things about 531 today. Glad I asked! :)

From what you have written above, you don't seem to have a clear idea of what you're after: on the one hand you want a vintage show-pony and on the other you want something cheap and of low interest to thieves.

Not sure I mentioned thieves, but I'll re-clarify in case it's ambiguous.

What I want is something pretty for <£200 with the above spec. Not because I want to be showy, but because I like nice stuff. I know it can be done because from time-to-time I've seen these exact things and I've seen other people get lucky on their hunts. E.g. the lovely black+chrome Columbus with Campy dropouts for £80 I got sniped on last week. Alternatively I can pick up an old frame and re-chrome and respray for £200 total. But the frame's got to be legit and lightweight in the first place or it's not worth spending my time on. Hence my question, really... if I only looked for Columbus stuff I'm going to take much longer.

Of course I'd love a £1000+ Pinarrelo Montello for my SS project but that'd be nuts for an all-weather weekday bike.