How about the 450 No2? Rim size would be close ,but having a huge powder capacity ,presure could be kept down. I just aquired a 450No 2 case (as well as others up to 700NE) and I,m thinking it will be good in a Ruger No1 ,but I wonder if we could get a spartan to regulate with it? I think I would keep a Spartan as the Cheap 45/70 it was made as for a cheap fun/pig gun.