FrenchTrains (Daniel): First let me say that despite your log on name I did not pick up on the fact that you were actually in France until you mentioned the difficulty of finding Lionel ! I worked for NATO (yes I know France was not an official member but had representatives on all our cooperative technology committees) for many years and was privileged to work with a number of extremely good French aviation engineers and to visit plants / test facilities in France a number of times. In fact, up until I left the committee I chaired (Air Vehicle Technology) in the late 90's all our meetings were conducted in both French and English.
So what am I writing for...well to add to the wisdom you have already received I thought I would add just a little more confusion. There is another series of passenger cars, which although they never came in a set with the big 763 actually look rather like the 613/2613 tinplate cars although somewhat smaller. I know that you mentioned you like "time period correct" and these were made during the same late 30's early 40's time period as the 613/2613 cars. These are the 1630 /2630 /2640 series which came in blue / silver (1630 & 2630) and the 2640 series which came in both blue/silver and green / cream . Note all of these are basically the same car with differences in coupler types. The "16/26" series cars are 9 1/2 " long vice the 613/2613 series which are 10 1/4 " long but their appearance is much the same.
Well so what would be the advantage? Well the "16/26" series came back AFTER THE WAR while the slightly larger cars did not and they ran from 1946 through 1949 in some color schemes. This might give you a better chance of coming across a good set. They all were numbered in the series "24XX" for '46, '47, & '48 and then changed to a "64XX" series for 1949 and then were withdrawn. They officially (post war) came with the engines numbered 221, 224, 675, 2025 & 2026 the latter two are " steam turbines". While officially in 0-27 sets, the 224 & 675 were top of the line engines in their day and of course the steam turbine was Lionel's absolute top engine in most of the early post war years. Post war, color wise, these came in both blue, green, and brown (the most rare) . Obvious differences pre / post war are the trucks and couplers. 
Here is a picture of my pre-war 1630 /1630/1631 consist pulled (out of the picture) by a 1666 loco and tender. While the set is pre-war the picture dates to about 1954 with the layout my Dad and I built in my parents basement - this was the first step up from an "around the tree only" layout as in 1953 we finally moved out of rental homes into our own house (I was 9) Note in the background is the turbine powered work train that "Santa" brought in 1947. While I was too young to pay much attention, I suspect that Dad bought this passenger set "used" because I wanted some passenger trains to go with our freights and new ones would have been way too expensive for the family after finally being able to afford a house.
OK Daniel I wish you good luck with your search for the Lionel cars.
Best Regards
Don McErlean
