I agree with the earlier posts from more experienced bowlers;however, If you want see what the feel is like when you have more or less finger in the ball try changing inserts. The difference between the front and back of a lift is roughly 1/16 of an inch. You might try turning the lift, front to back, so that you can shorten the span on either or both fingers. This will
allow you to put more, or less, finger in the ball to see what that feels like - without having to plug and redrill. I understand that this is not an option, if you don't use inserts.
It is easier to be accurate if the ball feels centered and balanced with equal tension in the fingers. The middle finger is stronger and some experiments with the differences between finger spans may be necessary. You might find that balanced tension in the fingers causes a need for some change in the thumb pitch.
Hope this helps.
--------------------
OnlyBowling