Started with a 460 and rebuilt to a 521 with a C6 automatic (Tom you can chime in now
.....Actually it was a relatively mild build at 537 HP and 580 TQ (through the Cobra headers as installed) but it would easily vaporize the tires through first and second and is the only automatic car I ever drove that would spin the tires on the 3rd gear shift. With that torque, you find yourself noticing the type of pavement on every road you drive on so you can deal with the smoother surfaces in case you wanted to nail it to pass someone and not spin sideways at 60.
It never overheated, but idling at a stop light in 100 degree Texas summer heat would make it climb to over 220.
Very fun engine but still pretty heavy as the only downside. Go for the 521 for relatively cheap and reliable gobs of power.