... True gas tank filler hose is not very pliable, it can bend but it isn't made to make a 90 degree bend. I am more of a "stock" kind of guy but I believe that the Rod shops will have what you are looking for to do this correctly.
Filler Hose:
Best new product. Awarded by: National Street Rod Association.Filler Neck: I'd agree with Carl, stay away from JB Weld. I am sure you can find a local fab. shop, muffler shop, radiator shop or hobbiest that would TIG or MIG weld a bung to a filler cap for you. Or set out looking for a cap with a vent:
filler caps with vent lines Filler Cap Vent Line Size: size it so it is the same size as the vent line.
John
