I'll second both sentiments. If a cast shooter is the goal and not necessarily historical accuracy, I personally would lean toward the Krag and re-barrel it with a Criterion barrel whose inside dimensions are much more consistent than a 100+ year old barrel that may or may not have been within spec when it was made and then had countless thousands of shots fired through it. I've been shooting cast bullets out of Krags since 1968- from lightweight "cat sneeze" loads to full throttle Arsenal equivalent loads and have come to grow a little fond of it. The '06 on the other hand is every bit as versatile...
Close your eyes and pick one.