Willymc;
If the bolt is removed, how thick is the metal? Some National Security units were quite good, some are nothing more than a different name on a Liberty. Giving us that thickness will tell the tale on what it is you've got. But, I'm not too hopeful of a vast amount of metal being there. That hole means it was hung from a "hook" on an assembly line when it was made. And that means that in all likelyhood, there's nothing more than gauge sheet metal at that point.
So, if you do run a wire in, once you've got the interior wired the way you want it, here's what to do. Get a tube of high-temp RTV and a computer cable 90 degree plastic fitting. Fill the hole around the wire with the RTV, and fill the fitting also. Then place the fitting over the electrical wire, which forces it into a 90 degree bend. Put a book or some thing on it overnight. Then, when the fitting is solidly in place, you can trim the excess RTV off. The wire with the fitting does not provide a straight path into your container. The path is filled with a decent thermal resistant goo, and you've got power into the thing, which is what you wanted.
900F