Hi, I just removed the drums on my z over the week end.
What I did was, knock the wheel studs in all the way, as instructed above credit to Lucifersam for the idea.
Then I used a hammer to tap around the front outside edge of the drum, until I could see a small gap starting to form about half way inside the hole, that the wheel studs used to be located in.
When this line formed I sprayed some penetrating oil in the gaps, while rotating the drum, and left it for a few hours.
I then came back and tapped the drum off from the back edge of the fins, straight in an outward direction making sure to tap on opposite sides of the drum for each whack.
Hope it helps,
Ahmed.
BTW. It's a Canadian car no one took care of, so you can imagine the rust.