Brian,
You are correct about about the QZ line, same cover just different surface prep and colors.
On your drilling, more info would be greatly appreciated like, axis rotation,speed,and tilt.
Remember pin to pap distance controls flare and cg determines weight hole placements on symmetrical cores. If it was me I would do something different then stacked, not say it wont work but I would try to have a different ball motions compared to your other balls in the bag. Your pro shop operator can help you with this, seeing that we dont know what surface you bowl on, oil pattern, etc. Hope this helps
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Rob Cabello
Motiv Staff
Motivbowling.com
bowlersuniverseproshops.com