A very old trick my father taught me with these brake rotors and drums is water. Water caused the rust, and believe it or not, water will help get it off. Get a couple of gallons of hot hot hot water, and pour on your rotor, if you can get as much between the rotor and hub as you can, then use the heat, and beat. The hot water will start loosening the rust, then heat will expand the metal, and the beating will get it off.
With drums, fill the drum as much as you can with water, at times we have had to pull the axel out and turn it on end, then put it in a bucket (cherry pickers are handy) then when it is full, heat, and it would just fall off.
I know this is the hard way, and is the last ditch effort, but hey, it works.
A large puller can also work some times too.