To find out information about a vehicle such, including a vehicle history and who the previous owners were, we would normally recommend trying an internet service such as Car Fax, Consumer Guide or AutoCheck. The vehicle history report these services can provide should give you enough information to determine if the car has been reported as stolen any time in the past.
To use these services you will need the auto's vehicle identification number (VIN) and pay a small fee. Unfortunately, prior to 1981, VINs varied in length from 11 to 17 characters. The internet services that can look up vehicle histories can only report on vehicles that use a 17 character VIN. Therefore, information on vehicles manufactured before 1981 is usually limited. You may still see if any of these sites can help you conduct your research on this classic America car.
If these vehicle history sites are unable to help you, try contacting the Department of Motor Vehicles of the state in which the car was last registered and see if they can provide you with any addition information. Also you mentioned that the car was already exported from the US to another country. The country in which this US classic vehicle was imported to may also have information. Try contacting the Customs or government agency that deals with the importation of automobiles into your country.