These are the grips I have on my SB that was built in 1962. They are an elk horn grip that is made by a gentleman on eBay. He makes these grips and is hit and miss on the listings. I think he is somewhere out west. I have them on all my 3 screw rugers. 6 of them. I love them! They are high quality and run 85-125 dollars a set.
They really make the older Rugers stand out. If I can find his info I will post it for you.
I have been buying grips for both old and new model Rugers. I am not sure about the blackhawk, but something was changed on the Vaquero some time around 2005. Two of my Vaqueros were made in the 90s and one made very recently do not take the same grips. The number on the frame will have a RED by it, indicating it is the newer one.
I think I participated in a discussion here about that maybe a year ago.
The Super Blackhawk (other than the Hunter and short barreled models) has a larger grip frame, the size, profile and location of the pins has not changed to my knowledge, so any modern Super Blackhawk grip panels should fit your late '60's vintage gun