Italian is larger diameter (36mm vs 35mm for Fr and close enough to 35mm for BSC) so that is the only choice if you have to retap. But since you say there isn't much steel there maybe you should consider going to a threadless BB. Mavic made a very nice one that you'll have to find on eBay or such since it's out of production. It requires you have the outer shell chamfered, not a big deal for somebody who has the tool and experience, but maybe beyond the home mechanic. YST (Taiwan) makes a much cheaper (and cruder) model that does not require chamfering, they can be had from www.biketoolsetc.com, among others. I would guess that the Mavic has an ISO taper and the YST a JIS taper, so consider what crank you will be using, too. (see how much FUN these vintage bikes provide for us?)