I think it'll be easy enough to coax back to roundness using a pipe or rod.

I sure hope you got a deal on the paint for all this trouble....

Depending on what you have for a setup you may find that it's easier to put the pipe or barstock into the vise and then just place the head tube over it and lever away using the rest of the frame to hold onto. That way you're not going to worry about it getting scratched.