I think he should be fine. From experience cold makes them move slower, and that heat rock is probably hotter than you think. He will love his new cage, and he should adapt very well to it. If he is too hot, some will soak in their water bowl.

I had a friend loose their bp in a car overnight. The temps got down to 35 degrees, and they didn't find him until the next morning. The first thing I told her to do was to get him warm. We heated up a water bottle until she could get him home. I thought he was dead. There was very little movement. In 24 hrs he made a complete turnaround and is doing fine now.

I am not a snake vet though, so if I am wrong someone will chime in. Congrats on the new one. You and your hubby will love him!!