Originally Posted by
NormanF
You could have a bike shop file the bottom bracket housing to the more common 24 TPI British standard, for which a bottom bracket is readily available.
this answer is misleading. 26 tpi refers to the threading, as in threads per inch, not the width of the shell which is 68 for a standard british bb. A good bike shop can retap your threads from 26tpi to 24 tpi to get you English threading. Cutting/Grinding 3 mm off of the bb shell width might be tricky and I've never heard of it being done, but I guess it could be.