There is some discussion on this in a sale thread but figure it could use its own thread rather than be lost in the sales forum.

Building up a 1976 Motobecane Super Mirage mixte for someone. I've got a frame and no BB. I was told here that if it's not french threaded it is likely Swiss. Either way, not English. At a LBS they checked it out and told me that an english threaded BB would work. I was very skeptical and told them its likely french or Swiss. They didnt know what Swiss threading was. They tested it and said it was all good. This picture if the result. Drive side went in just fine counter clockwise. NDS went in fine clockwise up to a point. This is how much threading is left sticking out. I know a little is bound to show, but this seems like a whole lot to me. They told me it was normal.

The crankset is Stronglight 93, on which I will only be using the 45t ring. This BB is 68x103.

As this bike is for someone else I want to make sure it's all done correctly and safely. Thoughts?