I also use the wood clamp method but rather than cut your blocks in the exact finish contour, use a slightly larger radius. The metal will spring back some unless you actually melt it. I have used both a high temp (800F) heat gun and a propane torch held some distance away and moving back and forth constantly. Heat it , bend a bit, heat, bend, heat bend a little at time. Straightening the deflectors will be the hard part to get right. You may have to grab them with smooth jaw pliers and get it pretty hot.