Bonjour,
This frame is definitely 1960's French. I bet the seat post is a 26.6, 26.4 or 26.0. The frame builder used the T on the head tube as an identifier, so I would say the odds are the frame is a T_ _ _ _ _ ? Go to classicrendezvous (dot) com and you might see the different builders in France and start working from there. Lots of luck and you will find it. Keep pressing on.
Cordialemnt,
John