I used the thinnest part first. I cut it on a band saw. I cut the two pieces the same size as the lugs on the engine. When I got to the 67" I had used all the thin section so I just moved up a little. This actually helped a little with the velocity stack clearance.

BTW the thrust angle is the same no matter what part of the plate you use. When you use the thicker part the engine will just be offset a little more.

David