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St. Sheldon suggests that using a JIS one would leave the cranks 4.5mm outwards of where they'd be with ISO...
In short, the difference between ISO and JIS, is the way they're measured: ISO from end-to-end and JIS from before the start of the 1mm taper.
In other words, 111mm ISO is the same as 109mm JIS.
Scilly.Suffolk
@Rhodrich
OK, so I did a little bit more measuring last night.
Whilst I couldn't fit the 111mm Campag cartridge bottom bracket fully into the shell without a proper tool, I could spin it in by hand, leaving a 3mm gap. With the crank installed on the axle, this gave me a chainline of 46mm, suggesting that with everything torqued down properly, I'd end up with a chainline of 43mm with this BB
So.... to get it down to 41mm, this would suggest I'd need a BB that was 4mm shorter: i.e. a 107mm ISO. St. Sheldon suggests that using a JIS one would leave the cranks 4.5mm outwards of where they'd be with ISO, so I'm not sure a 107mm UN55 would indeed work.
Miche used to do a 107mm ISO BB, which as a bonus was adjustable, but the more recent incarnation is JIS, with a flange on the RHS cup, so not adjustable. These days, this seems to be the only suitable BB I can find: http://www.totalcycling.com/en/gb/Kinex-ISO-Taper-Bottom-Bracket---107mm-Eng-Thread/m-18081.aspx