Much confusion surrounds the Ruger Single Action Grip Frames. Lucky for us, Boge Quinn has graciously allowed us to "link" a page from their gunblast.com web site. https://www.gunblast.com/Hamm_Ruger-SA-GripFrames.htm
the early one was a black eagle and the 1971 depending on the serial number range, pre fix 31 should be the silver ( Squashed chicken) eagles,,never know with the "parts bin theory" if carried over with the grips just what they may have put on as that is a "transition" period.....seen them either way, but my guess is, some folks put the black ones on instead back then.....
You will need black eagle grips with the pre-1966 style medallion for the 1964 shipped gun.
For the 1971 gun, great chances it will be black eagle if 30-95000 or earlier. 31 prefix and later would most likely be silver eagle.... in between those serial numbers could be either.