It's a good find. 1967
Overlander International. People do search for them. I would place the 1967
Overlander very close to the top of the bell curve graphing "Best Airstream Ever".
The Overlander that year is 26' 11". Airstream designates it as 26 feet. "International" is a trim upgrade from the standard "Land Yacht". The upgrade is mostly superfluous fluff but does change the wood interior from all Ash to all Walnut. I don't know why walnut is an upgrade over ash, but walnut was a popular rec-room paneling in the sixties..
You can dig through the Airstream website and find a cut-away view of it with quite a bit of information about its components. There were two floor-plan options, mostly about the beds.
As to value, there is very little value in its original furnace, water heater, etc, so if they don't work, that's OK. It'll need some electrical upgrade, and you get to learn PEX while re-plumbing. Most often there's floor rot, but that is expected. The rear view picture doesn't show gross "separation" (look that up on this site's google search), so that's another plus, but hard to tell.. Separation repair isn't the most fun, but is do-able without a helper.. You could find someone with Vintage Airstream experience to look at it with you.
The 67/68 trailers were the last of the truly vintage "twinkie" style body. They're incredibly durable and rebuildable. I'll say the pre-1969 Airstream is an easier restoration than post. They're relatively uncomplicated. There's no shortage of restoration parts, and no shortage of restoration advise.
It is a worthy project, and you'll have a decent camper after you throw $10K and two years of your handiwork at it. It is usually not a project to make money on, but if you're clever, you can stay even with the market..
$15,000, should put you safely on the road, and you'll wonder why you ever wanted to be tied to a piece of vacation land.
Generally speaking, any rolling "rebuildable core" of this vintage is worth around $5k if the frame and skin is good. It's a plus if you can find one that has not been modified or gutted and all the glass is original Corning. It will probably have thirty pounds of hickory nuts and worse, stashed in all its hidden cavities, again, expected.
If you walk around this trailer and it "speaks to you", and you're ready for a project, it will be rewarding.