Search for "dropout screws" on eBay. Lots of choices. I'd suggest the ones Dave Moulton's sells, Fusoman69. Yours are probably some funky diameter and threading since it's a French bike. Unless you're doing a museum quality restoration, it won't hurt to do a little drilling and retapping. There's also a Park tap on that eBay page. Be careful if you use it. Little taps like that like to break off in the hole. Use lots of cutting oil, make a couple of turns when it's cutting, reverse it out, add oil, make a couple more turns, repeat.