Power Booster ?'s

Bill,
You didn't say what car model it is for, but on my 69 Dart, the booster itself is NOT plated at all, but the 2 heavy brackets to the firewall are gold cad. I also don't have the other 2 long, thin brackets you refer to, and I see no evidence of them ever having been on this car, but I do see them in the service manual. I can't comment on their finish.
I also think that the different assembly plants used different vendors, so what would possibly be correct for a MI built car may not be true for an LA built car etc.

Please post a picture of the other 2 thin brackets to the inner fender/firewall if you can. I'd be interested in seeing them.
Hope this helps some.
Good Luck!

George