Bottom Bracket size issues
Yes, you can use the suggested alternate BB cartridge sizes.  

The thread (68mm) has to match precisely, but the width of the axle can vary.  The problem is whether 1mm more or less will affect your chainline on the drive side.  Relatively minor changes can upset the extreme cross chain positions.

So if you're a big-back-cog rider, get the narrower BB, or if you ride a lot on the smaller rear cogs, get the wider BB.