Rule of thumb is, for any distance you go over an inch from the Center of your grip with the CG, you will add that amount of side weight above the 1 ounce that is allowed per USBC rules.  So with your 5 3/4" PAP and wanting to put a 4 x 4 drilling, you will more than likely put at least 3/4 ounce of side weight in the ball before balancing.  But with that much top weight to start, I can probably bet you will have more than I'd say 1 1/2 ounces of side weight. A ball with that much top weight really doesn't need the CG kicked out too far to make it strong.  I would lay this ball out with the 4 x 4 you want to do and then put it on the scale to see how much you might have to take out.  Your PAP is very close to mine.  I might try a 4 1/2 x 4 1/2 drilling and that might get you closer to an ounce of side weight.  Good luck.