Is the rear derailleur of the same vintage as the shifters? Campy changed the derailleur's actuation ratio in 2001.
My interpretation of post #1 is that the OP is having indexing problems while downshifting because the statment is: "does not index when climbing the cassette". This sounds to me as if he means the problem is when shifting toward bigger cogs, though this is actually downshifting. If this is correct the problem may be with the shifters, or possibly a bent derailleur hanger, or a problem with cable routing at the rear derailleur. A problem that I've seen recently was caused by the pinch bolt washer tab pushed up against the cable effectively changing the actuation ratio slightly.