It will depend upon the density of the wood and your ability to control the moisture in it. You definately have enough wood to start, at least for an experienced craftsman. When you get the bow up to say 20" of draw, you should be able to tell if you have extra wood. If you haven't seen more than say 1/2" of set to 20", you could probably take 1/8" off the width end to end. Might cost you 2" of draw length, or there about. And if you get away with it you'll pick up at least that much in cast. I guess my point is a layout isn't necessarily the last word. In fact, it's just a guess to get one started. How the bow reacts to being worked, and near the end of the project how the bow shoots, should guide the design, in terms of width, of the finished bow.