As someone who has been making and exhibiting 60" for the last several years I can tell you that the same image settings don't translate well at that size. For truly excellent results you'll need to develop your images differently for that size and take under consideration any "gallery wrap" areas (the sides) if you intend to stretch them and present them without a frame. Think about the final product you want to present (including surface, stretching depth, framing, etc) and work backwards, tailoring your files for that final product. Find someone truly talented and experienced at working at this size and make many smaller cropped test prints at the full size. Shipping final prints in a tube shouldn't be too hard but you'll need to consider stretching at your final destination, and the implications of transit afterwards. Work with someone local if possible, or consider acquiring the right printer if your quantity of prints makes it feasible.