The thought had occurred to me to swap the processors. I'm not sure what or if anything else would need to make the journey from the donor to the original clusters. But the customer was getting anxious for it to be done. I really wasn't up to diving into another rabbit hole with a customer on my back. So I decided to leave it in a running condition and told him to take it to the dealer, where they can address all the issues.
When I said "this one went nowhere", that had nothing to do with the support from Rosstech. It was in reference to the fact that I wasn't able to complete the job, due to the fact that I could not successfully write the data I copied from the original cluster to the donor cluster and restore the vehicle to a running condition with the donor cluster installed.
The help I got from Rosstech was useful in determining that the problem with the ambient air temperature reading was actually in the original cluster. They also generated and emailed the coding to restore the ABS module. Had I been able to get the cluster to work, I would have used that to complete the job.
The VCDS is a diagnostic tool capable of OEM type diagnostic functions. Unfortunately that doesn't include capabilities outside of OEM type diagnostics, such as matching a used cluster to a vehicle. But apparently, neither does the VVDI2 in this case. Or if it does, I wasn't able to find it.
Although I had purchased the VCDS several years ago, the guy at Rosstech was kind enough to spend quite a while on the phone, helping me track down the source of the problem at no charge. I posted their normal support terms above.