ZL1 rear is nice don't get me wrong.. But for the price you are 3/4 of the way to the 9"/12-bolt combinations. I'd put a DSS 9" in there and call it a day. The new gear setups being done by DSS now are a lot better for gear whine. The price tag is not as bad as you think compared to the ZL.
2013 ZL1 - 9.82 @ 138MPH (Stock Shortblock)
2011 Camaro SS - 9.87 @ 136MPH (Stock Shortblock)
Installation, Parts, Full Fabrication, EFI Tuning