My Wayne 515 had a dent like yours. As Brian said take a torch and heat it to glowing red . I keep a bucket full of Ice and water near by with and old rag in it. I toss the cold wet rag on the metal to cool it fast. Might have to do this numerous times. All of a sudden you might hear a pop and the dent will pretty much be smooth. Ben doing this for years while working on old cars with dents such as yours. Good luck with your project.

Anything oil and gas.