I’m assuming that since you used z71 wheels you have 6 lugs. eBay listings describe the technical specs of OEM wheels 16”x7”6lugx5.5 with 31mm offset.
The diameter of you current wheels + tires is 31.9” overall. The stock size (265/75/16) is 31.6” so maybe your speedometer reads a tad higher than actual speed but close enough.
All that to say, just about any GM half ton wheel from 1994-2014 16-18” appear to be the correct lug pattern and offset while allowing tires to keep near the factory rolling diameter of 31.6” (otherwise you’d need the car programmed or have an off speedometer). You can of course get into the 20-22” range but that’s silly on an OBS to me.
If nothing else you could search for 6-5.5x31mm offset wheels on various distributor sites.
