http://baseballcardpedia.com/index.p...Topps_Heritage
Bookmark this site for the future. Looks like the French text (OPC) backs may be around 1:20 if the same insert ratio holds for the other types of packs.
Since there are 50 white bordered cards, and one for all 500 cards in the set, seeded at a 1:67 ratio, you can calculate a reasonable guess as to the number of French text backs unless they are an exclusive to hobby.
67 x 500 x 50 = 1.675 million packs.
1,675,000 packs / 350 / 243 = approximately 20 of each OPC back. (Technically, Topps can't call them O-Pee-Chees because Upper Deck currently owns the copyright to OPC).