OK, I just did some measurements on a cam. Anywhere between the "o" in "TOP" and the center of the key could qualify as the high spot. The "p" in top is sort of iffy, as is the trailing edge of the key. Aw heck, nobody gets them that accurate with a feeler gauge anyway. If you want to get it right, use a timing fixture. Easy for me to say, I make ’em.
