Value of RV 440/727

A coworker of mine has for sale a 440 out of his old Winnebago motor home, with a freshly rebuilt 727. As I understand it, the industrial/RV 440s and transmissions had specific parts that are useless in cars. Accessory brackets, different exhaust manifolds, different tail shafts in the transmission, etc.

What would be a fair price for a running engine with transmission? Considering the cost of parts and effort to swap it into a car. Thanks.