Dan,
If I understand your reply, I suspect you might have misinterpreted the drawing on that page. As I read it, the cleat in the drawing IS mounted through the cap rail, as Kevin described, and NOT through the bulwark. (The drawing is indeed somewhat confusing, in order to show the hawse fitting through the bulwark. Although I cleaned up the manual and created the online versions, I did not make the original drawings.)
As in Kevin's reply, mine are mounted such that their centers are 7-1/2" forward of the Genoa track and 30-1/2" behind of the aft lower shroud.
I did not mount them myself (they were probably factory-installed). But I would have to say that their locations have been ideal in all situations. Personally, I would opt for thru-bolting with backing plates, rather than lag bolts. Lag bolts can make a good structural bond in fresh timber, but your cap rails are probably 40 years old and who knows how well they were kept up by previous owners? I had some ares that rotted totally through.
I use my cleats not only used for spring lines at the dock, but also for rafting to another boat (like the pump-out boat), for tying up my dinghy next to my ladder at anchor, etc. I couldn't imagine getting along without them!
Jack