Private Purchase and Export in Belgium

Hoping to find some local knowledge here-- I am planning to purchase a 1974 model-year car in Belgium which I will immediately export to the USA. I am comfortable with my plans for shipping and as well for US customs, but concerned about the actual sale process in Belgium, as well as the export process (if any).

To the best of my knowledge, the car originally came from Italy since new, and the current Belgian owner has had the car for around two years. I believe the car is NOT currently registered for use on the street and has no license plate. It is possible that it has never been registered for street use in Belgium--it has been part of a collection.

Can someone advise what paperwork is required for a proper private party car sale in Belgium? And what to watch out for? Any systems within the country to ensure a clear title? Do I need to visit any government offices to complete the sale? Anyone able to confirm the name of the Belgian auto authority (is there an equivalent of the German ADAC or similar?) as a resource?

Many thanks in advance.

JS