Right, it's not a collector's item and functionality and "flavor" are important but originality (unless it's a pristine example) is not, in my opinion.
The derailleurs can be replaced with non-plastic Simplex (which may be labeled "Peugeot") or something else. People like Suntour Cyclone derailleurs, I sort of like some of the better Huret of the era. Huret stuff doesn't get a lot of love, but they made some decent stuff (and a bunch of crap) and it's cheap. This is sort of a "flavor" thing to me -- French bikes::French parts. If you are interested in Simplex, look for metal derailleurs with crapped out wheels -- Suntour of the era are a drop-in fit (as well as repro Suntour wheels from the likes of VO).
The cotters for the crank may be a different diameter than "typical". Pays to measure.
The freewheel is probably Maillard and is likely metric/French thread. If you decide on rebuilding the wheels with alloy rims, check out the hub first as metric/threaded freewheels are not nearly as common as 1.375"X24tpi. Those look like Normandy Sport hubs and English threaded examples are readily available.