depending on how deep the rust is electrolysis may leave you with a pile of crumbs..not worth the risk in my opinion..maybe just coating it with a mix of water and elmers glue to prevent further decay and put it on the shelf..cool find
I'm by no means a expert but don't you need to flake stuff off enough to at least see if there is a fuse? I could still very we'll be a bomb if it still has powder in it.