Most that you find will be rusty and probably dented on the underside of the pipes. I've had one I didn't want to cut-off the centerstand mounting loop and have to bend the other, so I sold it on here to another member.
They do sound great, though, I think my favorite sound, and I've had the three 4:1's commonly found, Kerker, Mark's, and UFO. Be prepared to pay dearly for something in decent shape.