I have an SP101 and it is built like a mini-panzer tank. If I had to shoot a double powder hand load, I would choose either my SP101 or my GP100. I love my S&W revolvers, but the Ruger revolvers are just massive.
So, I would not anticipate any damage to the cylinder. For pricing, I'd see what you can get that exact model for on GB, and use the case issue as a reason to offer half of what you can buy new for. That should cover anything that comes up.
Good luck and let us know how it turns out.