How many speeds are you working with?

Your relative (i.e. "converted") chainline will, of course, be much more critical with a single speed than it will with a multi-speed (particularly if more than 10 spds).

S.B. indicates a 122 cart. BB length, while another (older?) guide recommends a 118 (while using an "obsolete" LP-26. I'm not sure if there's a diff between the old LP-26 and newer UN-26). Either way, you're only looking at an approximate R.H. BB length diff of 2mm between the two. However, your relative* chainline could actually end up being as much as 5 or more mm further outboard.

Either 122 or 118 should work well enough on most multi-speed bikes. A single speed could be another story...

*Below is a link with a section that covers "BB interchangeability" and "relative chainlines" (see pg. 10-3). http://www.esense.be/bike/Barnettmanual.pdf

Btw, did you find any rust/corrosion in the BB shell area? If so, I'd lube everything up with marine wheel bearing grease. You might even consider drilling ~ a 1/8" hole through the very bottom of the BB shell while you've got it all disassembled (this will, of course, allow water to drain from the BB shell).