Not really sure Dave. My unrestored 70Z with Z87 doesn't have a highly reflective "chrome" appearance, but I thought that might be just 50 years of aging. Maybe they did have a satin appearance to the chrome applied to plastics?...not sure and asa ou pointed out, even Chevy identified it as satin....hmmm....Yeah, it is a bit interesting.
Nearest I've been able to determine the the lower dash was "chromed" from 70-72 and in 73 they went to painted edge over a black base.
When I say "chromed" in quotes, I haven't seen any that were a real good, reflective chrome finish, except those that have been rechromed from services like this:
i know mine wasn't. The back of mine has the word "bright" next to the part number and the finish on the back is pretty much satin like the front. Might ask COPO for a closeup of his. Hopefully others with well preserved Z28-Z87 interiors can also chime in.
The fact that GM even called it satin seems to reinforce this.
This is different than the edging around the gauge bezel. That does appear on mine as a very reflective chrome and has been observed this way by me on other cars.
Open for comments......