Older Motobecane conversion I recently acquired an older blue Motobecane Mirage with a great frame and paint.  I have stripped it all down and salvaged everything I can (frame, front wheel, handlebars, front brake) but now I'm left with a quandary.  

What type of bottom bracket/crankset/rear wheel will I need?  

There is something bizarre about the bike so I've read but I can't find a solid answer.
Having converted two 70-something Motobecans, take to your best local shop to figure out what fits your bottom bracket. 

As Mikes asked Is the issue the French bottom bracket? Or reverse threads? 

As a last resort, Velo Orange has a bracket that will work. DO get rid go the cottered cranks!