What is a reasonable price to pay per hour for restoration work on the body of the car? I'm not asking about drivetrain restoration and/or installation.
Depends on the part of the country, where the shop is located, cost of overhead for the shop and other facts. Also allot of shops don't do "restoration" work just body work
and remember everyone has a different definition of "original" and "restoration" Getting on the same page as an owner of a body chop can be a very difficult task - one that doesn't not always work out. Way too many stories that demonstrate the difficultly.
Shops that have a proven past (check the references) are likely a good place to start since it might be easier to reach a common understanding of what you want and what they can deliver