Is there something wrong with the original equipment Stronglight cups, I wonder? In a pinch, you could just turn the original spindle around to mount the drive side arm on the short end of the original spindle and get a pretty decent chainline:



Otherwise, I've successfully substituted Campagnolo and Sugino spindles into Stronglight bottom brackets.

Finally, Velo-Orange sells a metric thread bottom bracket cartridge in a variety of widths:

Grand Cru Bottom Bracket, French Thread