Neither.
If I were in the market I would be buying a C6 Vette Grand Sport. You get the Z06's dry sump (with the manual), wheels/tires, anti-roll bars, and body. The suspension is different, but most have said it's the best ride and handling of any C6. It weighs more than an Z06 because it has a steel frame instead of aluminum, but you also get to keep the targa top.
OR
Go back to the Mustang and buy a new BOSS. I never liked Mustang's, but the new 5.0's won me over, and the BOSS is just BAD.