I guess I didn't take very good pictures when dismantling my 1962 292, because I can't find out what bolts into these holes in the heads.
empty - a set on Flickr
They are all the way to the back and not covered by the intake. For now, I just plugged them with short bolts, but I was thinking that at least one of them would be used for a ground wire. Is that correct, or is there another purpose?