Blast!
I got mine out by putting a piece of wood on top through the gas door and prying on it to force the tank down. After that it came right out. Mine was stuck to lots of ancient undercoating. Still haven't decided weather to fix mine or get a different one from Steve @ Indiana Pontiacs. The bottom of mine is rotted. I have an NOS sender for mine as my gas gauge never worked since I've owned it.
Glad to hear you're driving your wagon and having fun.
Rob...