Howdy, all! My friend gave me a Chorus CT square taper carbon crankset and I'm curious about the BB spindle length. It's a 68mm shell and for one reason or another, all the information that I could find (browsing catalogs) pointed me toward the 102mm spindle since 111mm spindles only seemed to be for Centaur. Anyone know for sure? Thanks!

Yes, and you need a ISO/Campy taper, not a 103mm JIS taper. 111mm also used for triple.

Got the 102mm and the chainline is way off. Going to try a wider spindle. According to the Campy catalog, the 115mm is recommended for my seat tube width (32mm).

115mm is for triples with 32mm seat tubes. Are you sure you're measuring chainline correctly? Campagnolo carbon compact square taper cranks were only available for a couple of years between the introduction of compact cranks in 2005 and the introduction of ultra-torque in 2007. It's not like there are several versions of these.