'68 Dart Instrument Cluster Refurbish

As far as costs, and cost versus quality, a search for vacuum metalizing or plastic chroming will turn up a number of experiences (and some speculation you can ignore).

https://www.forabodiesonly.com/mopar/search/2714836/?q=plastic+chroming&o=relevance
I can't help you with that particular dash details as when I did it, I was focused on the ralley panel.
As I found there is no substitute for asking and looking for unrestored originals as reference.