IIRC, Springfield Armory concluded in trials that the 1:12 twist was the most accurate for the service rifle, but the military wanted the capability of shooting the 220s so they went with the 1:10 twist. The 1:12 became something of the 'std' for the 30-30, and still is great if you dont go over 200ish.
Now, that info was for factory/service smokeless loads, with reduced velo, cast bullet loads you need more twist to stabilize the long heavies, especially if you are going sub-sonic.
I would think it would work nicely for 180 or more cast bullets at something like 1150-1350 fps and have great wind drift figures, though trajectory will be a bit loopy. It might be a real sleeper for CF cast bullet silhouette matches.