KZ 440 Gas cap

Hi folks. This is the gas tank from a 1981 KZ 440 deceased estate that I've been given which I'm trying to put back on the road.

My question is, does this look like the original OEM gas cap?

At this stage I haven't been able to unlock it with the ignition key, but not sure if the lock is frozen or it's an aftermarket item and needs a different key?

Thanks.

I don't know if it's the stock fuel cap, but I'd guess yes. 
That style of fuel cap is typically hard to replace as they don't come up for sale very often.
Not sure, but I don't think the lock cylinder is "keyed" to a specific code, so any correct style key should open it.

www.partzilla.com/catalog/kawasaki/motor...0-b2/fuel-tank-81-b2

Thanks Martin - I thought it looked pretty stock and period. I'll persevere with the oil and wiggling. Might try and get a spare key cut first just in case the inevitable occurs!

No eBay APP ID and/or Cert ID defined in Kunena configurationDoes the ignition switch key open the seat lock & helmet lock? 
I would probably try to get a new/correct key cut to the code on the seat & helmet locks,
since those two are probably the originals.  It may not matter but might eliminate some doubt. ???
Also, I could be wrong about any key opening it. but I'd be surprised if that was bad advice. hee.
My fuel cap is the 80s rectangular stye and I have a couple of spare fuel caps & all the keys open mine.  

For reference. here's one that I think is the same as yours. I've never seen a key cylinder like that.

Thanks Martin. Yes the key I have works in the ignition, seat and helmet locks no problem - so is the right key for the bike. It's just not happy in the gas cap.

I'll try a few different keys that we have around here and see if there is any progress, otherwise I'll haul the tank down to the local locksmith.

Just an FYI.  AFAIK, there isn't an aftermarket or universal fit fuel cap available in the correct size. 
If you'd like the measurements of the fuel cap, I saved a pic w that info. I'm pretty sure it's the same as yours. 
Nerdy originally posted the pic & measurements (but I combined the two).  gotta give credit where credit is due. hee.

Thanks everybody, did get there in the end. Penetrating and thin oil down the key slot over a period of a couple of weeks. Wiggling the key and slightly twisting back and forth whilst relieving the pressure on the cap spring.

The 32 year old gas was varnish, but the neck cleaned up with a stainless toothbrush and some phosphoric. Cleaned out the tank and flushed with further phosphoric and then treated with a clear weld through primer I use here for preserving fabricated parts - Epiphos. Leaves a thin impervious coating and really bites into steel treated first with phosphoric. Tank was not leaking, so I'll not go any further with it - particularly that I plan to make an alloy tank later in the year once the bike is back on the road again. We have a regulation change coming in in October whereby any bikes not currently registered for the road, have to have ABS to protect the numpties who can't ride.