Could you just use a dual tank valve from any pickup within the last 30 years? Just solder one line shut and run your fuel line to the other. I believe that most of those were electrically actuated, so a key lock switch should not be too hard to come up with.
I had thought that when I get mine done I would put a relay in the wire to the electric fuel pump. (It will have the engine and fuel system from a 1989 TBI 454, including electric pump in the fuel tank.) I like the idea of the key lock switch, though. Hadn't thought of that myself.
