I plan to use raptor-liner underneath my car, but just recently I used it on the interior also.
I wouldn't think it would do much for sound suppression, but it does prevent steel reverberation and helps to seal the cabin up even better. I plan to insulate on top of it and finish with carpet, but my car is a whole lot closer to stock than yours.
There is so much going on in your interior I think foam shaping will be your friend to simplify some of the panels to make carpeting a whole lot easier.