I would tap the threads to English and sell the French threaded pedals.
rhm is right, I think. I have a set of English-threaded Olimpic 64s that doesn't fit my French-threaded Stronglight 93. I'd consider trading pedals with you--on the condition that if your pedals are also loose on my crank (I don't know whether my crank threads are on the large or small side) that we trade back.
By the way, my engineer brother calls the phenomenon you describe--fit problems that result from one component being at the high end of the normal range, and a mating part at the low end--as "tolerance stack-up," which I think is kind of a nice phrase.