Velo Orange has a good selection of French-spec components available.
http://store.velo-orange.com/index.php/components.html
If the paint isn't in bad shape, I'd keep it for the "cool old French" look. Otherwise, consider spending a few bucks to get it powdercoated. Probably won't cost too much.
One of the issues with these old French tandems is that the stoker's top tube is generally really short and makes the rear cockpit very cramped for all but the smallest riders. It looks like your tandem has a stoker seatpost with a lot of setback, so that should help some. But, if your potential stoker is much over 5'2" or so, make sure you do some shorter rides before you commit to doing a longer ride on it.