The wheels are Mavic Championnat Du Monde Monthlery rims with Campagnolo Nuovo Tippo quick release hubs or Ofmega hubs, the Campagnolo kit was optional.
You have Simplex Criterium front and rear derailleurs, check that the pulley wheels are in good shape on the RD. For normal riding look for Vittoria Rally/Corsa CR or Gommitalia Champions (700C is correct as noted already).
If you want to know more from me, PM me and I'll gladly help. I have a Gitane TDF myself and have recently overhauled the entire bicycle bit-by-bit over this summer except for the stem. I highly recommend trying to pull it out as soon as you can and really clean/grease things up in that area. Right now, mine is jammed stuck....it really sucks. IF the stem moves easily, tilt the bike upside down as the bearings do not sit in cages, they are loose in stronglight head sets.
Got any pics? I'm curious to see it.