The No.18 catalogue gives 112mm as the standard for a double - that's a "68-SS" Campag axle:
http://www.campyonly.com/history/catalo ... log_18.pdf
It's slightly asymmetric, with a 3mm bias to the right.
There were a few variations in bottom brackets around that time though, as well as the question of thick and thin cups. I've never quite been able to make head or tail of it, to be honest. A few days ago I was puzzling over a slightly later document that details the changes, axle codes, and the question of thick and thin cups. I can't find that pdf right now, but if you PM me a valid email address, I'll send you a copy when it shows up.
Many other manufacturers made Campag-compatible axles at the time, and you may find a Mavic, Ofmega, Gipiemme etc. will do the job. Some of the better Japanese units were also compatible before the rise of the JIS taper. Older Dura Ace or Suntour Superbe Pro used Campag tapers.
Calmes dans le demi-jour
Que les branches hautes font,
Pénétrons bien notre amour
De ce silence profond.