The Emerald would IMO be a good choice, but if it feels too heavy, I'd pass on it. Mixing weights is not good for timing and playing routine - even though it could be that, if the ball is drilled properly for your hand, it fits well? Best solution is to ask at a pro shop, or trust youir feeling about the weight. Just to not use the ball just because it is for free - better do it right from the start!
Weight hole is usually used to get a ball back into legal limits of static weight - most of the time, when the CG is placed outside of the grip center, towards the PAP. In some cases it is used to fine-tune a ball's reaction.
When a used ball is plugged up for a re-drill, the balance hole can be plugged, too, if the new setup calls for it. That's no problem and does not harm the ball's performance.
--------------------
DizzyFugu - Reporting from Germany
Confused by bowling? Check out BR.com's vault of wisdom: the unofficial FAQ section