Still researching my options and associated costs.
At this point, however, I am leaning toward restoring only the auto-leveling portion of the Z55 suspension by using air shocks in the rear, as the total cost to fully restore the full Z55 suspension (electronic and air), using GM OEM parts, including front struts, rear air shocks, compressor, and control module, will probably exceed $3500, and this assumes that the height rods and wheel sensors are all still on the truck and fully operational. I simply cannot justify spending that amount of money on this truck for this specific work, as I do not believe that the incremental improved handling from the electronic portion of the Z55 suspension would be worth the incremental level of investment to include it.
For restoring the auto-leveling by replacing the front strut assemblies with new strut assemblies and replacing the current coil-over rear shocks with rear air shocks, and a new compressor and control module, I am currently looking at front strut assemblies by Arnott SK-2954, the rear air shocks by Arnott AS-3430, and the compressor by Arnott P-3430, and the control module by ACDelco 15095294. This can be accomplished for less than $1500. And, perhaps, I won't need to replace my existing control module.
I'm still researching and evaluating, but this is where my current mindset is.