I know I'm hitting the easy button on this one, but I've looked pretty hard and cannot remember the correct placement for this ground wire and I'm anxious to get all the last odds and ends worked out. I remember it was pretty greasy so I cleaned it up really well, but don't see it in any of my disassembly pics. I believe one end goes to the rear of the block, and I would assume it goes somewhere on the firewall, but can't figure out where the spade end connects..?
The ground wire mounts on the back side of each head and the flat end slides into a small bracket mounted on the firewall. Both heads have a ground strap and there are two brackets on the firewall mounted lower than the heads.
Oh shoot, I miss read the subject as 1960, not 69.
Oh well, D Mirrione is correct, with his descriptions.
I hope the 1959 pics are helpful and are likely not to be far off from a 69 - but I'm not sure.
Have fun,
Steve B.