Originally Posted by Doc Watson
well i want mine to be as original as my pocket can make it so I suppose original....
FWIW In the case of the SPF GT40 which is probably similar or exactly original in this regard, I think it's held in by two ~6mm bolts at each end and then maybe one or two under the demister screen. I'm basing that on vague memory and this discussion: Dash Removal
I don't believe any of the other fasteners in that discussion have anything to do with retaining the dash itself.
The FAV parts book on panel R shows a couple screws at each end but in the price list they are simply two of 14 self tapping screws used somehow, so that's not much help.