It is almost impossible to find a paint shop who can cross those old numbers...and if they do come up with a paint for you, you won't know if it is exact or not. I would advise to not stress further. Use a piece from the column support, e-brake handle, shift rod or pedals to get a scan for the dark gray. Which should be the same as the dash top except a non glare was added to the mix.
For the rest of the truck, use whatever is there to scan. If there are no pieces to scan...........get some rattle can paint that is near, paint a test piece, see how it looks and then scan that or give the shop the Rustoleum/krylon number.......or paint the truck with quarts of that paint off the shelf. Chasing old numbers will not work. If this is not a Barrett-Jackson restore, you will be OK driving it around and not be pulled over to get harassed about it.
FYI: for the inside of roof, I HAD a tip in the tip section to use magnetic sign vinyl. The tip, with my name on it, is still there but has been swapped to a different tip. I don't know what has happened to it. I emailed management years ago, never got a response.
Anyway, check the tip section under paint and interiors and get some pointers for your panel.
It would also be nice if we could see what your interior looks like with well lit pix. Just to get a feel for what you see.