Jesus dan why are you doing this to us? You are selling everyone's favorite car to get another badass car that Im sure will be everyone's new favorite. Man this is hard to see.
But in the spirit of asking for opinions, heres mine.
1. Mod the GT you already have for cheap, pocket the $60k or whatever you had to spend.
2. 2013 Boss 302. Will be ready for boost and grab lots of attention.
3. C7 Z51 if you want to blow the load. Get it from Mike Furman - Criswell Chevy in MD. You will get invoice and they will ship your car to your front door for peanuts. Hes the #1 corvette salesman in america and they sell more corvettes than other chevys.
4. C6z. Eh not too keen on this unless you get a minty one unmolested, then molest it.
5. 2011 GT500. Has 5.4 aluminum block. Add 3.4 whipple and break hearts of those that paid $60k for 13+ GT500. Remember that 662hp 13 GT500 really only makes around 590rwhp and that can be had very easily on the stock blower from an 11/12 GT500. They are high $30k to low $40k right now.
6. As you can tell, Im not a huge fan of the CTS-V unless you are going to leave it be and dont plan to race it. Even the coupe is too nice to wrench on in my opinion. Just drive, rinse and repeat.
Thats my opinion. And the more I look at the list, the more a C7 Z51 auto car would probably be your best bet for all around performance. Should rip at the 1/4mile and 1/2 plus will dominate a road course.