Seeing if the instrument panels are reprogrammable and interchangeable.

You're better off sending the cluster to one of the many places that have sprung up to handle all of GM's problems. You will keep the correct mileage too. These are real high-failure items so any that you would find in a salvage yard are likely to also develop problems. Then you'll be right back where you started. If you do an internet search for "instrument cluster repair", you'll find hundreds of listings. I use Advanced Auto Electronics. Have been very happy with their service.