Back when I was a parts counterman,I often had guys come in looking for a special pipe or tubing for gas tanks, and radiator conversions..
Many times a walk out back to the exhaust pipe racks was all we needed to do,we just looked thru them all till we found one with the right diameter and bends (or "close enough"),and I sold them that,with the stipulation it couldn't be returned if modified..
I have used radiator hose on fuel tanks,so have many of my old customers---I know its not recommended ,but I never had one leak or freak out from exposure to gas--diesel might be a different story..the hose does get rock hard after awhile though..