Sure - just get the same size single line and tape them together with electrical tape. I did that on the tank for my "57 Lark and it works fine. As long as you don't get gas on the tape (it will dissolve the adhesive). Just leave about 6 inches untaped on the ends.
I think the question is to convert from double line to single line. You'll have to find a fuel pump small enough to mount to one of the bypass covers and drill through a "centered boss" and still have mounting screw bosses. I do not know which pump will work for your motor.