You don't specifically say if he wants top sell all the vehicles or just some. If he has a computer he can do research to find out what others have sold for. As for the 41, check and see what 40 sedan deliverys have sold for. Here's a start.
https://classics.autotrader.com/clas...ivery-for-sale Be reasonable and honest. Also here:
http://www.allcollectorcars.com/clas...edan-delivery/ Let him make the final decision. I think the market is changing in a downward direction for OEM cars as younger buyers are now buying the cars of their youth like muscle cars. Street rods with all the modern conveniences seem to be doing well, however.