346 mikey. Because of the rear mounted trans there’s really only one option for an auto trans in a C5 'vette, and that is the 4L60E that’s in there. They can be built w/ many upgraded internals and can take a lot of power when done right, but in stock form they aren’t super-duper. In fact you might want to have 1st try throw a mondo-big trans cooler on there while you’re at it. You should be fine at the power level you’re going to be at, especially since you’re not going to be non-stop racing it. But heat is the ultimate enemy of the '60E.
-TJ