I recently purchased a Brunswick C-System 3.5 and it turns out that is a factory second.  I've found that the ball's overall gross weight is a little higher then the first quality variety of these balls.  The ball's gross weight is 16lbs 4oz.  The person i purchased the ball from said it wouldn't cause any problems as long as I drilled the ball a pattern and put a balance hole in it.  I am just wondering if this is all I will need to do to ensure that my ball is legal and rolling the way it should?  Also I know that the USBC allows a maximum differential of 3 oz from the top and bottom of the ball as well as a 1 oz differential from either side of the ball.  Could I encounter any issues with these rules? Thank you in advance for any help you can provide me.