Jeff, the wheel studs are through the brake drum, right. I'd say you could do with out screws if you have to. Keep soaking it and let it set if it don't want to come. Panther [censored] keeps working, sometimes it takes a while. A few light taps now and then help move the penerating oil move deeper. Drilling may not be an option. They have been heated and cooled so may times they may be harder than chinese arithmetic already. Might be able to use a die grinder to remove the screw heads. Would still have the rest of the screw to deal with tho. Or are you just after the drums?
I would use heat only as a last resort, but then the gas axe is always the last thing I use. Good luck. Mike