I have an elm stave that I plan on making a self bow from. It is 68" long and I want to make a 66" long bow, nock to nock. I'm keeping the width 2" out to 1" past mid limb and then taper to 1/2" at the tips. I was wondering what thickness I needed? I'm wanting to build a 50-55# bow, and I'm also thinking about recurving the limbs. Thanks!