78mm seems wide even for Raleigh, 71 and 76 are mentioned more often. Had a look on t'bay but couldn't find anything promising by searching Raleigh or "26" in the BBs category.
I'll see if I can find some cottered cranks I like, then ponder the BB some more.
Yes, but if not 5mm per side, I still need to find a BB and crank!