A virtual Dyno said this...

If you can tune it, I could see a fairly stock cammed magnum with a 200 shot getting to 520-530. How long will it live there, depends on if you can tune it.

Edited to add;
I have a magnum crate that I bought from westech that was used as a dyno mule. With a small comp roller cam and an rpm air gap, headers and a 750 it made 365 so it’s not too far of a stretch to 530. Maybe not at the wheel though.