Elm has been used in Northern European bowmaking for thousands of years, and you are certainly not going to anger many people here by saving a piece of Yew until you got a couple of bows under your belt. Good yew ain't cheap and cheap yew ain't good.
If you are shooting for a bow over 40# draw weight, I would recommend going a bit over the 1" width, but you could still get a 50+# bow from a full 1" width. You may get a bit more string follow with the narrower profile, but a little string follow makes a sweeter shooter.
If this is a board bow, be sure to use a simple backing, like lightweight canvas glued on with Titebond II. If it is a stave split/sawn from a tree with an unblemished growthring on the back, forget backing altogether and let the wood shine thru.