Joe, report back on your results after the weekend "adventure". If you go for the welding technique, the tech term is "weld the hell out of it". You are welding fairly thick material, nut to stud. This is not sheet metal type work. Besides you want a lot of heat into the stud quickly so it can expand against the cold block and crush the rust and corrosion and then when cooled will shrink back to size leaving a microscopic gap in the crude that is holding the whole thing together.
Best of luck!! You will get them all out.
Best of luck!! You will get them all out.