I'm really not familiar with French military history and their uniforms, but from what I've seen of photos of French troops in Vietnam during the 50's, their uniforms & helmets seem pretty similar to the gear used by US troops in Korea. Some photos show them wearing berets and officers seem to be still using the typically French peaked caps.
Did they keep using this gear into the 1960's? If so, you could try converting the Imex US Army in Korea set (or even a WW2 US infantry set). The peaked caps should be fairly easy to scratchbuild and for berets, you'd probably find some amoungst the various British WW2 sets.
Don't know if that helps, but it's a suggestion...