Call Wa state DMV, BUT...Be be prepared for the run around. They dont just hand out previous owner or tag data
Also, alot of computer systems didnt go computer until about 1983 or so Allot of older paper data wasnt even entered into the DMV system: There was just too much paper to electrons tranfer that had to be done
The VIN is a big key to getting the help you need: Maybe they can track it down. But then you need soemone willing in the DMV to write a letter with the facts that would help you out: Finidng someone willing to do that in DMV will be the hardest part
Sometime though, if you keep trying, you might ge ahold of a person in DMV that understand why you really need, and may help
A formal letter to the Wa DMV may help as well Include in that letter a copy of every formal regulation that you must fullfill in your country to register, and you might get help.
Persistance will get what you want. But it wont be easy................In the furture, dont post your VIN on a public forum. Its just good personnal security measure