Are you changing the rails on a 2025 table? Old threads and methods are good for old tables. Just because some company used to carry K66 and no longer does, or vice versa is really irrelevant. The profile has not changed over the years.
My point being if you aim at contact point on anything other than straight in or very close to it you will miss. That is the only time ghost ball center and contact point are the same aim line. Ghost ball center is always correct.
If Dr. Dave says that is correct then both of you are mistaken. The pocket facings are at angles so then the center point of the ball when in contact with that point would be perpendicular to that angle. You statement would be correct if the pocket facings were at 45 degrees, but they are not.
If you could move the balls where the centers are on that line the contact point of the rail facing would be well inside the points. In other words, if the points are exactly 4.500, then the centerlines of the balls would both be almost 1/8" outside the line that goes from point to point.
Very misleading picture there, if you look at the angle on the face of each side of the ball ang then draw a perpendicular line out at the ball contact point then it looks to me like it is easily correct, you could also simply measure point to point.