Boxer Firewall Options

I am now starting to reverse entropy on my boxer resto I'll update my resto thread soon. One quick question- I'd appreciate thoughts and advice regards the freshening of the firewall. The material appears to be a glued insulation product then coated with? silver stoneguard. parts are brittle and peeling- I would prefer not to try and remove the entire panel and I was thinking that it would be potentially reasonable to fit in a rigid modern insulating product and then re-coat with silver stoneguard -.
I would really appreciate any advice- I linked the image plus a couple of the beginning front-end reassembly.


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