1969 Barracuda (w/AC) Firewall Insulation Diagram?

You said it. Too bad nothing came with instructions or warned me about the yellow insulation material. Feels like it's under my skin. I have almost destroyed the heater box plenum with the Spectra heater core. I dug up the old one and the new is not a good match!

I took lots of pics on disassembly and as much on re-assembly. Not always easy to find them but I took them!

My core was still good and box repair was more cleaning / resto gaskets and minor fixing.