The original fuel line was copper.
Your motor looks like a nice example of an early Elto Cub. Using a reinforced fuel line would look very out of place IMHO.
Just as a note, if you ever pop the flywheel off be careful with the spark plug wire. The attachment point on the coil is a known week spot and many if not most Cub coils are open because of this.
Does the motor have spark?