I have a black walnut stave perfectly straight, 72 inches long, a hair over 2 inches wide by 2 inches deep. I would like to make an eastern woodlands style of bow with it about 66 to 68 inches long and in the neighborhood of 40 to 50 pounds at my 27 inch draw length. My issue or problem is this- along the length of the stave which would be the future bow's back there are shallow grooves and ridges. When looking at the corner edges of the back of the stave, these grooves and ridges are no more than an 1/8th of an inch higher or below the back corner edges of the stave. When making the bow, can I basically "ignore" these and proceed as if they aren't there or would it be safe to flatten the back and back the bow with rawhide?