I'll agree with the 470 and 9.3x74R also. There are a couple of shps around here where you can buy both off the shelf but I agree with 400nitro that the vast majority of doubles shoot handloads.

I also agree that, to me, caliber is not an issue when buying something and I tend to stay away from 470s becaused of the additional cost that caliber brings. I would guess that you would pay a 2-5 thousand dollar premium for a 470 over say a 450#2 of equal condition.