Windshield pin placement 67 GTO

I have finished the windshield channel on my 67 GTO. Now I'm ready to install the reveal molding pins for the clips. I can't find much information about where to install the pins. I think they install 1/2" down from the top edge? About left and right, i found a diagram but the numbers don't add up. I know there shouldn't be a clip where two pieces join. How critical is the placement of the pins? Any information would be appreciated!
Thanks,
LET