First I would roll the engine through its range of motion and see where the roller is moving on the valve tip. It will sweep back and forth across the valve tip as the lifter goes up and down. You would like this range of motion centered on the valve tip. If it is not centered, sometimes you can shim the rocker shaft assembly up a little to change this range. Sometimes though there is nothing you can do. If the range of motion doesn't get real close to the edge of the valve tip, its probably not worth worrying about.
