I spent a while trying to replace my collapsed dash/bulkhead insulation with stuff like the original Citroen padding. The 2cv people in Halifax said that I could have some, but I'd have to cut it to shape myself, and go up to their place to fetch it.
Eventually I gave it up as a bad idea (why buy stuff that tends to sag and collapse?) so I bought some stuff called brown bread, which is pretty thin and does a good job of deadening the noise. It's easy to cut with scissors, it's simple to work with... and has an adhesive backing. I was able to cover the main part of the bulkhead with just a couple of pieces, and made a patchwork of the fiddly bits.
It looks fine (has a reflective finish, giving a kind of space-age ambience!
) but when I get round to it I'll cover it with leatherette trim (the same as the stuff I've used on my door cards).Hope this helps.