Thanks, all, for the input. Yeah, I don't want to drive myself crazy over a millimeter or two -- but this is my first build involving derailleurs (I've built fixed gears) and didn't know if chainline is even more crucial for smooth shifting. I'm gathering parts slowly so I have time to get the correctly spec'ed length, but I have a silly fondness for the old serviceable-type BBs.

A.Winthrop, you may be correct about the 119mm for 6207; my research on it was not thorough.