the two standward bb witdths are 68mm (english) and 70mm(italian)...((then theres french, etc...) so depending on your frame, you should use the correct one, cause the other wont work!

what you need to be concerned with for chainline is the spindle length... depending on what cranks you have and what rear hubs you have, you need to get the according spindle length for the bb. standard seems to be about 111mm.. but depends on the entire setup. theres a wide number of spindle lengths available in all threadings of bb's. i used a 111bb on a 126 rear spaced frame, and it worked fine.

go here for some info: http://www.sheldonbrown.com/chainline/

good luck.