I think it's a '74-75 Tour de France; the Stronglight headset is original but not much else. It's from the years Gitane Pacific imported them. The Interclub frame from those years was pretty much identical - I owned 3-tube 531 Interclub for a while - but kitted out with lesser parts. The Stronglight P3 headset makes me think TdF.

Stock parts would have included Mafac brakes, Simplex derailleurs and Stronglight 93 cranks. From what I have read, the ride quality on a 3-tube 531 in this size should be indistinguishable from full 531.

Cool bike, good upgrades, would love one of those in my size!