Gold (24k) was $35/oz in 1970.
Late in '71 we went off the gold standard (backing the dollar with gold) and it went up to around $38.00/oz. Around $45/oz in '72. and onward.
A shop I worked at in '73 went bonkers and changed their 14k gold line inlay on a shotgun contact build to .99 Fine Silver because of the cost increase.
The plates look like they could be 10k gold which looks remarkably like most common brass alloys we see. It tarnishes about the same as well.
10k gold is 10/24th gold, or 5/12th pure gold alloy. (Take the alloy number (10k, 14k, 18k, etc) and make a fraction over pure gold (24k) to get the fraction of purity of that alloy)
Around that time ('71) 10k sheet gold would have cost about $20+/oz. Add labor of course for the job.
Not an extreme amt, though taking into consideration what we made back then, it wasn't pocket change as it is today.
$30 back then could have paid for just the 10k gold to do that job IMO judging from the pic.
I'd guess the plates have a peg or two each soft soldered to their backs that are inletted into the grip wood and the plates and pegs epoxied into place. The pegs giving extra strength to the assembly.
It could be brass,,I could be all wrong.
So..I would take the grips to a jeweler or one of the We Buy Gold places and have them test the metal for gold content. Simple test.
At todays values, even 10k gold, the plates at scrap value have some $$ not to be tossed aside.
If you don't care for the gold and grips replace them. At least you'll know what you are dealing with if you decide to replace them and possibly get rid of them.
Nice revolver BTW!.