There was a discussion about SR crank failures a month or so ago. I looked at my cranks but apparently did not look close enough, and I looked at the spider area most critically instead of where the crank broke. Mine that broke was an undated track crank just marked "165 PISTA" with the 144mm bolt circle. The crank broke at the eye where the pedal mounted. Now looking at it, it appears that the metal at the break point is discolored in one area, which seems to indicate (to me) that there had been a hairline crack there for a while. I had also previously noticed an occasional 'clicking' in the BB area, and had tightened crank bolts, chainring bolts, etc. in an effort to clear that noise up. Apparently the noise was an early indication of pending failure, although I now believe that if I had looked more carefully I would have seen the crack.
Since having a crank break can be painful, (I hit the pavement rather quickly) I would suggest taking another close look at your vintage Campy cranks. I had previously retired a 175mm SR road crank due to a crack at the spider. (Now I have two orphan left crank arms)
Ben Sanford
Falls Church, VA