I dón't know about the flair, but I wouldn't use copper for a fuel line. Fatigue (vibration) resistance of copper is quite low compared to steel.
I'm just about to ready to bend my fuel lines for a 1955 Imperial Sedan. When I noticed a flat copper flair not a double flair. Has anyone ran into this problem and do you use the double flair tube with another fitting???
Warren Binegar
1955 Imperial sedan & Newport