If you give those Duco numbers to a paint guy nowadays, you'll just get that deer in the headlights look.
What I would do is get some of the base color and either add some silver to it to get it lighter or sweet talk your paint guy into lightening it up for you. Who's going to tell if you don't get it exactly right? If it looks good to you, that's all that counts.
I did run across some paint chips (although they're electronic so not real dependable) at TCP Global. But they were two different tones of the Cambridge Grey Poly (see attached pic). Tim's Tech tip on paint colors call the interior colors Medium Tan Metalli-Chrome and Dark Tan Metalli-Chrome. So there's lots of confusion around interiors.
As I mentioned, Jim Carter's interior paint was too dark to match my original, but their steering column paint was spot on for my truck.
I saw another pic of a guys '51 COE for sale in the swap meet that suggested that the whole speaker grille and center of the glove box door was all the same color, and appeared to be lighter than the dash itself. Found that pic too, in case the truck gets sold and the post deleted.
My plan was originally to mask the higher ridges with 3/16" wide tape and spray the lower areas, leaving the ridges polished stainless. You could spray the whole thing with the lighter color, then tape off the ridges and spray the darker. I think that would be easier than spraying darker first and taping the valleys.