I recovered my dash bits, too. Similar, got mine at a fabric store. Black marine vinyl. Unlike the factory stuff that's fairly thin, the stuff I found had a bit of a padded backing on it.
The top was easy enough, used upholstery spray adhesive, and a bunch of small clamps and clothespins to hold it tight as it cured.
For the bottom, it was a bit difficult to get it to wrap cleanly, as I didn't have a high-end heat-gun that could shrink up the vinyl around the complex 3-way curve... what I did was, trim to little overlap, one one short vertical seam. My intent was to find a trim-piece to cover that seam, but haven't yet.
I left the original in place, and just covered over.....
-L
'72 SIII SW 88"
'60 SII 88" RHD