ORIGINAL: Kevin1963
If I use heat to get the firwall out, is it pretty much a sure thing on screwing up some covering around that area?
Kinda depends on the heat source and how carefully you use it. You WILL need to work slowly. If you can get the engine mount and all the other stuff out of the way you COULD make a cardboard template too. A number of small pieces around the edges (to get into the corners easy) and all taped together into a final template. Use light cardboard or poster board that's easy to work with.