As far as the 260 Rem goes, that would be an acceptable solution, but it would require a custom barrel (or build) as well. Savage does not appear to offer its target rifles in that chambering...though, I think they used to.
I'm not too concerned about setting the shoulder back...maybe I should be...but I've seen 338 norma shortened to 7mm Fatso, and there are some people who use WSM cases to form what amounts to a SAUM case with an improved shoulder. So it is doable, its just a matter of trying it, and seeing how much work is involved...I expect to have to turn the necks to my desired thickness, but hopefully that will be it.
I really just wondered if changing the rifles chamber & dies, would be a simple matter of shortening both or if I would run into problems there.