If you are a high tracker and clip the thumb hole as you say, then the horizontal measurement of 6" over is probably close...but your vertical measurement is probably a little up on the VAL if you are not clipping the finger holes as well.
--------------------
That which doesn't kill you will only make you stronger, that which doesn't make you stronger is a waste of time!

Trace your FIRST oil ring with a grease pencil.  Then place the ball in the spinner with the PAP side up.  Adjust the ball position until the track line is the same height all the way around.  Turn the spinner on and watch the line.  If it wobbles, adjust the ball position until it doesn't.  With the spinner on and the track line steady, place the grease pencil lightly on the top of the ball.  The pencil will migrate to the very top of the ball.  Press down with the pencil and mark the spot.  This is your PAP.  Now place a piece of white tape on the PAP and take the ball out to the lanes and throw it.  If you've accurately located it, the tape will appear stationary until the ball begins to flare.  If you're using a nonflaring ball (best choice), it will appear stationary all the way down the lane.  If you're using a flaring ball, have someone else watch the tape for you, because it may begin to flare before you pick it up in your sight.  If the tape doesn't appear stationary, the PAP is not located correctly.  The most likely error is in tracing the FIRST oil ring.  You can either start over or try moving the tape a little at a time until you hit the right spot.  Good luck.  --  JohnP  (By the way, the easiest way to locate a PAP is with an Armadillo axis finder, but I'm assuming you don't have access to one.)

To locate your PAP with the Armadillo, trace the first oil ring in the region beside your thumb and finger holes.  Place the ball in a cup with the finger holes up and the thumb hole down.  Place the 'dillo on top of the ball with the "axis finder" on the PAP side of the ball (right hand side for a rightie).  The axis finder is the small flat area with a notch in the middle.  You will notice a series of arcs on the left side of the 'dillo.  Move the 'dillo around until you find the arc that best matches the marked track.  If it doesn't exactly match one of them, estimate between the arcs.  Now go to the axis finder and draw a line across one of the flat edges past the notch.  Draw another line from inside the notch past where it intersects with the first line.  The intersection point is your PAP.  Now mark it with white tape as I described earlier and procede.  You can do this procedure (after the track ring is marked) quicker than you read this.  Good luck  -- JohnP  By the way, the 'dillo is also the fastest way to lay out a ball using the standard "PAP to" dimensions, such as 5" x 4".  Just line up the 5" arc with the pin AND the 4" arc with the cg or mb and mark the PAP at the end of the axis finder.  You will have to move the 'dillo around on the ball surface until both arcs match up.  If they won't match up, that layout is impossible for the pin out distance of the undrilled ball.  Then procede as usual.