Being in the Smoke Chamber, shouldn't get to much hotter than under the hood of a car running down the road in July in Texas ????
Great idea with the hood springs. I would have thought they would stick into the cook chamber too far, but they don't look to bad.
Lined them up, traced the opening, pulled apart and cut, realigned and welded.
I cut the FB opening first before welding to CC. Mine was a "special" case where the scrap steel sheet for FB was not big enough for all the FB sides to be "full" pieces. I chose to make the FB side the one I made out of 2 pieces (spliced) The bottom 1/3 was welded to the FB. The top 2/3 piece was marked for CC opening against CC, then cut, ground, tacked to FB and checked for final fit before final weld.