Ford 601 Broken Bolt in Gas Tank

[AL Farmall Boy]

Does anyone here have any good suggestions on removing a broken bolt (size is between a #10 and 1/4" on my bolt gauge) in the bottom of a gas tank from a 601 Ford tractor. This is the small bolt that holds the fuel shutoff/pickup on. I was trying to install a gasket and block off plate so I could clean the tank out and I broke the bolt off into the gas tank. How can I get it out? The bolt was already out/loose and I reinstalled it too tight and broke it.....it didn't take much. So far I have used a center punch to and (2) different sized left hand drill bits to drill it, and one of those spiral type EZ outs.....what next ?? I hammered the EZ out in there pretty tight and tried turning it but I am afraid I'll break it off too. My center punch didn't line the drill hole up perfectly and I am at a loss for trying to get it out now. Being such a small bolt makes it really tough. Haha, next time I'll just use a rubber stopper to plug the hole!!