I think the 115.5 is assymmetrical, as well. It's intended for several different cranksets than the 111's were.

If you bought your first Campy BB new in the box and you kept the little booklet, the booklets usually have a complete directory of what cranksets require what BB. You should be able to find the exact spec requirements from that. Or you can get on the Campy website, look for the Technical Literature section (may require some trial and error) and find the specs.

I fully agree with you buying one bb and have it be the correct one, that's always to be hoped for. I think that if you know the campy spec you will be the most likely to find one with the least amount of compromise. My opinion on that based on my recollections is as follows: The 111 asymmetrical has, if I recall, a 1 mm difference on each side, rather than being balanced. The biggest positioning error you can have is 1 mm. 115.5 has one end about 4 mm more offset than the 111 symmetrical, which means the biggest positioning error is up to 4 mm. The 1 mm error in chain line is hardly going to affect indexed shifting of the front rings. The 3 to 4 mm error of the 115.5 could affect rear shifting due to the fact that chain offset angles in big-little and little-big positions will not be how Campy engineered them. These two problems are worse than the ones due to the 1 mm each side position error.

The current Veloce series BB costs in the $40 to $50 range and is 111mm symmetrical, I think. The "low-price" Record 111 assymmetrical is indeed cheaper than I paid, but the current Veloce is less than half of that (less than a third of what I paid!). You might think it's worth a try.

I've installed a Centaur compact, a Racing Triple, several Records, and a Record Triple in recent years. I think my Record Triple uses the 111 asymmetrical, but I don't recall exactly. When I had the BB out on the table I compared its measurements to those of the 111 Centaur bb, and found them to be very close in offset. To replicate the data exactly I'd have to disassemble two BBs, and to compare with the 115.5 I'd have to disassemble a third one. If you can't find good info on the Campy site, I can try that over a weekend.

At least nobody here is telling you to use Shimano, yet.