1956 Dodge Hardtop, Stripped Oil Plug and Oil Extractor Options?

If you have an air chisel or access to one I'd try that first, grab one of the flats and try to pound the plug counter clockwise. This can be done with a hammer and cold chisel if you don't have access to an air chisel
Second option would be to weld a nut onto the plug to give you something a little better to put a wrench on, plus the heat will help break the plug free.