Rob74 wrote:cheap enough Tandem might suit someone. Seems odd. Would ask about the bottom bracket threads.
I have a soft spot for tandems.
I would be fully expecting both BBs to be standard British threads, given the tension pulley rather than an eccentric, or are you concerned with condition?. I'd prefer a ghost chainring for the purpose of chain tension but that's just me. Of most interest is the Arai drum brake, which can fetch some good money on its own.