26 TPI BBs are rare now, but I think it's not so hard to find a spindle -- if it's the cups, well . . .

If the BB housing is 70-71 mm wide, you could have it retapped Italian (their standard is 70 mm wide housing, and the threads are larger pitch dia. than English), but make sure that there's enough material in the BB for that. Then you could get a reasonably-priced IRD cartridge-bearing BB (made in lots of spindle widths) and a pair of their Italian cups, and you'd be in business.

Disclaimer: I haven't done this, but it works as a Gedankenversuch.