Looks like a 0 offset 20 inch wheels and stock height truck Keep in mind the ZR2 sits big. It's 83 inches to the top of the cab at the B pillar with 35s. That's basically the same as a 6 inch lift on a 2500HD of yesteryear.
You don't need that AEV kit for 37s. I think it might be more beneficial if your gonna run offroad hard.