Sound deadening, firewall coverage

[71harrison]

Hey all, I am going through and stripping down the entire interior to sound deaden, rust repair, and install aftermarket AC. I have the whole dash apart and am at the firewall looking at the factory deadening/heat shield. I was wondering if anyone has recommendations to remove it and add deadener/insulation behind or just just stop at that point? I am going the route of SecondSkin Spectrum and their FireWall Ceramic coating. Additionally any "while your in there" knowledge of things to fix or check would be great.

Thanks

 

[jblueridge]

Replace and/or lube heat and ac control cables and things they connect to.

 

[RhinoRig]

I ditched the original insulation because it was dry rotting and useless. Put the cheap stuff (noico) down and has made a world of difference.
While you’re in there, take out the heater blower fan and clean out the mouse nest that’s been there a decade.