You can't dependably rely on the measurements if the grip is in the ball, or even if its out, if it has significant wear.
When the grip goes in the hole, the hole compresses it a slight bit.
How about you go to another pro shop and ask???
I won't deal with a pro shop that refuses to give me a copy of my measurements.
I always have them with me, so that if my equipment gets lost when I travel, I can get something drilled up.