Good points gentlemen. I think I will pass on installing them on the '68 for the reasons provided. We won't discuss the '67 as that is in a totally different realm for this forum...
As J_Speegle suggested, I may trade or put these on the market, but it would still be interesting to know how to determine MFG. As I don't really know what years these would have been installed or available prior the the '70's, would you know? Curiosity has got the best of me now.
As Bob mentioned, I did not know the difference between originals and repros is the brightness of the fins, that is good to know.
Thank you again for letting me pick your brains.