So, you can't feel that bounce at low speed? A neighbor had a similar experience on his 2023 Sierra at around 40-60mph and it went away after installing the new tires from 4Wheelonline plus the alignment.
Update with photos once you're done with the body lift. We're looking for a similar setup on the incoming Z71 project. It recently got 18" wheels from 4Wheelonline and new rotors and will fit 305/70 tires.