Assuming you don't want more than two holes for the fingers, you can also have either a thumb hole or a balance hole. If you have a thumb hole to use occasionally, say to shoot spares, the static weights must be legal based on both the grip center between the fingers and the thumb and the grip center between the fingers. This greatly limits your layouts and for some combinations of top weight and pinout distance may be impossible. If you never use the hole to grip the ball it is a balance hole and can be placed anywhere the static weights are legal based on a grip center between the finger holes. You can always drill any of the holes deeper or shallower than normal to help meet the static weight limits.
I've never known a no-thumb bowler that wanted to use more than two finger holes, if that's your situation you'll have to contact the USBC for clarification. -- JohnP