That's a pretty standard 4 speed 500 kick start Bullet, the "basic" model. Looks like you've caught it in time, the alloy will polish up and the chrome might have got a bit pitted in places but won't look too bad after scrub with some wire wool and chrome polish.
What's the story behind the non-UK front number plate, any clue from the previous owner? It does look like an official export model, only with a custom seat, aftermarket silencer and Lucas 564-alike tail lamp.
If you get a duplicate V5C for the bike based on its current registration you might find out a few more details of this bike's history, I think might tell you if it was an unofficial import.
Unfortunately the DVLA sting you for £25 if you didn't get the new keeper slip off the old V5C.