I have very recent experience.
Among the normal things (log books, all maintenance and repair records with proper approvals), make absolutely sure you have a good Certificate of Export.

Talk to a Designated Airworthiness Representative for your area before you
make the purchase. (DARs are listed on the FAA website ):

https://www.faa.gov/other_visit/avia...RDirectory.pdf

Good luck! With a little precaution it could be a great transaction.