There do exist low profile 1" metal tire valves with good effective gasoline-resistent neoprene seals:
A set of four is under $10. I am certainly NOT reccomending that you use these to modify an EPA-compliant metal can.
1) Don't remove the inner valve core.
2) Don't drill a matching hole near the central handle, and don't de-burr it.
3) Don't fish the valve stem and seal in through the spout hole with a piece of coat hanger, and then do not grasp the stem and guide it into the hole.
4) Do not thread and tighten down the special washer and nut wrench-tight.
5) Don't remove the valve cap when filling or emptying the can.
6) Don't loosen the valve cap when changing altitude in the mountains.
Always respect the laws and the politicians who make them.