I'll bite: ask your brother to read any marking on the crank: if it's Italian (like Magistroni or "house branded" Lygie) then I'd bet the BB is Italian threading, despite all the French componentry, since it's still likely an Atala shop product. BTW the saddle is an early Selle San Marco, before they typically added the "Selle" to their name, and they are kind of collectable to some folks. I sold one to a guy in the East (Coast, not Japan) for $90.