Of course, when I started my Reply, John hadn't Posted his info, nor had the two other Replies been Posted. I went to Post mine and got the infamous "This Page cannot be displayed". I got everything ready again, and got the message that there had been a Post since I started mine, but didn't want to take the chance of losing it all again, so I Posted my Reply anyway.
That being said, about the only thing I can add is that on my '67, the lower radiator support oval holes (which are the same size as the uppers) do not have, nor is there any evidence that they ever did, any plugs.
Bob