Here is what I came up with. Using a very rigid plastic 1/16th inch joiner, I cut the metal repair panel to fit after I squared up the existing hole with a dremel tool. It needed this to be welded anyway. But my dash will never be perfect and heating up that area would need to be closely monitored. So I searched for and found this joiner. Very solid!! One side is kinda has a round profile and the other side is straight and flush. Worked good with the slope to the dash downward and the straightness under the dash knobs.
~ BD. "You won't find me in an old folks home" Pioneer Florida Cracker 1958 Apache Stepside 1958 Apache 1/2 ton Panel 1959 Apache 1/2 ton Panel