a frame builder could build a bike with any tubing they want and use any BB shell size. 68mm is british road size and what all japanese, english and north american bikes use (to the best of my knowledge). Sorry I can't help with the tubing but I think this one might be for the CR list.
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1 Super Record bike, 1 Nuovo Record bike, 1 Pista, 1 Road, 1 Cyclocross/Allrounder, 1 MTB, 1 Touring, 1 Fixed gear