I saw a newer steel bike on another forum equipped with an older campy crank, one of their MTB offerings - looked like a C-record era road crank, but sporting two rings in 'compact' configuration (50/34 or 50/36?).

I believe that crankset was a triple (110/74), but only running the two rings. Looked very elegant on a new custom steel frame, and would look equally so on an older one.

A viable sort of option, IMHO. Even if you're running a crank designed as a triple, no one's holding you to use it as such - provides many more 'vintage' options. The particular example I just cited would be a great work-around for Campy purists wanting to mess with gearing in this way while still matching kit of the era...probably not the best specific route for most, of course! I think that Campy MTB equipment ain't cheap or plentiful. A nice 80s Deore XT unit, or something like that, might provide alternative aesthetic options at reasonable cost.

It would likely be most practical to just source one of the Sugino cranksets mentioned in the posts above, of course. I have one on reserve to fill just such a need as soon as it (inevitably) arises. Nice cranks, and reasonably priced.