I weighed the difference when I installed mine. If I remember right, the 12" swap with Global West control arms was 7# heavier than stock stuff per side. I weighed each assembly as a unit, not individual parts, so I'm guessing most of that gain is from the bigger rotors.
But if you dump your stock GN wheels and get just about any decent modern alloy wheel instead, you make all that back and maybe even end up lighter. Like, my GTA wheels are 17# each, vs. 25# or more for a GN wheel.