Firewall Insulation

[lkt1954]

I'm starting to finish the interior on my 69 C10 and would like some input on what I'm planning for the firewall.
Current plan: install flatline barrier material on the firewall and the put a firewall pad (with insulation )over it. I will use 3M adhesive to attach the pad to the flatline material and glue the clip heads in the holes (smooth firewall) to cover up those holes.
My thoughts here is that this will provide both sound deadening and insulation as well. The floor will be carpet.
Does this sound like a good plan or would another rout be better?

Thanks