Rob,
I doubt that those will work... IIRC, the gxp brakes have a caliper that sits in a bracket that mounts to the knuckle, where the g-body caliper itself mounts to the upper section of the knuckle...
find a complete spindle/brake assy from a 98-2002(?) blazer/jimmy 2WD... it's a direct bolt-in, no mods needed.