The only real trouble with re-chambering it, is the magazine length - the 2.5 case has a loaded length of about 3/10" too long. Well, that and getting the barrel off for re-cahmbering without destroying it. I've not been able to get a '96 barrel off without ringing (slicing) the barrel ahead of the action ring to the depth of the threads, just to relieve the hoop stress. Those were military actions though - perhaps they used a shorter wrench to put sporter barrels on with.
; The standard 9x57 should be perfect and in considerably more powerful than the .303 or .30/06. It's in the same ballpark as a .358 Winchester.