I have the Mini-14 riser with the "C" length limbs that produce a 56" bow. My draw length is 29.5" and I am right on the limits of the bow, but it shoots very well. I don't think you will have a bit of problem with the 56" setup you are describing. On the other hand, you can't compare a Morrison to a Shrew Classic Hunter as far as the lengths go. A 56" Shrew Classic Hunter can accommodate a draw length of more than 32", but the 56" Morrison Mini-14 (or Mini-13) ILF is maxed out at 29.5" of draw. Get the 56" Morrison you are thinking about -- you will be extremely pleased with it! Or if having a somewhat smoother draw is more important to you than having a shorter length bow, go up to the "D" limbs and a 58" length. Either bow is great.
Allan