If your rebore was to be on a Contender for a very small, light carbine I think that the .357 Max would be an unbeatable choice; but since you are starting with the Encore why not give yourself a bit of room to stretch if you want it with a .35-30 or a .35-40. They keep your desired rim, have great necks for cast, can be loaded down to match the little guys; but can push bullets 200 grains and over (the real sweet spot for .35s) much better.