check the size on current cd jewel cases, and you can always put it on the back, this is an assigned barcode, right, not one you just made up?
you need a manufacturers code or the use of someones, then an inventory number, i am assuming you did all this. barcode is one of the bigger problems getting into a national outlet, but a local store (like a recording of a highschool band at a local walmart.
quality is more important for a good read from a scanner. the barcode should be at least a quater inch high and good quality.
oh, did I mention quality?