I emailed both LaBella and Pyramid about strings that might fit my AGB200; LaBella never returned my email (I'm sure they get hundreds every day... can't answer them all, I suppose), Pyramid responded almost immediately, as well as a follow-up question.
So I bought the Pyramid flats. I like them, but then I like flats.
Bottom line, any "Beatle-bass" set make specifically for the Hofner will likely fit without an issue, keeping in mind the smaller tuning posts will benefit from a smaller taper at the end of the string.
I'm looking forward to trying a set of the GHS medium scale flats should they become a reality.
-Alex