XXXXXXXXXX,
Your old guy should be okay. My recommendation is more common sense then anything. Keeping him in a cool environment and limiting his time outside is the best course of action. I live in Florida and see people that have huskies or other artic breeds and they do okay. The big thing is making sure he has shade and plenty of water. he is going to get hot, but should be okay in that weather. If you think about it, there are probably a large number of shepherds in Arizona that work on the police force. Best of luck to you and your guy on your move.
Dog Veterinarian
6 years of veterinary experience, 3 years veterinary surgery resident trained