This is one way to make the heat shield. But if you don't own sheetmetal equipment. And your using aluminum sheet. You can cut the length you need , including bends, and make it in pieces. Make the center piece first. Going from memory 7 1/2" wide with 1 1/2 " 45* leg each side. You can clamp this to a bench or patio block, add a large hammer. Then cut the side pcs to mate up to this center piece. Bend the 45* leg on the end, pop rivet the two legs togeather. The same each side.
As far as the header pipe goes. I think my roll of wrap was ???I'm not sure, 25' or 50' , it was $30. bucks on Amazon. I removed the pipe from the header to the muffler, wrapped using all the wrap. So I simply ran out. It went to just the back of the cab, I wish I had more.