It legaly possible. I had done it a long time ago with a 67 Camaro. I forgot exactly how, something about one wrecked car and clean title and another car that was a rebuilder. It actually came out on the title. Again I have forgot most but I know my car ended up having two vin numbers on it
IE you take your wrecked WRX and another wrecked title and car and rebuild using both and depending how it is rebuild you would actully have the US vin on the Japan car.
Maybe you should ignore this post, since I am confused. Your best bet would be to call a body shop and ask them how they do it with rebuilders.