the shelf will depend on if you are having the bow bend through the handle some, which you may want to if you have a draw length of 28" you can taper in the handle area and add a leather shelf, just leave enough meat the the area not to make it weak. I do shelfs on some of my bows, only about 1/4" then fold a piece of leather to make it wider, or add a sliver of wood or golf tee. I really like a 64" bow for my hunting bow so yours should be good. the dimensions keenan gave are great for a shorter bow, just leave the belly a little bit radiused, helps reduces the amount of set.