Up to this point in time my discussion has centered on shaft mounted rockers. And on shaft mounted rockers the roller contact point on the valve tip will not change.....I love saying this.......even if you remove the pushrod and throw it across the room.
To change the roller contact point by using a different pushrod one would be using a stud mounted rocker arm.
I am currently studying the Jan, 2007 article on the Crane shaft mounted quick lift rockers.