What a gorgeous beasty!
Appears to be a 1″ axle and a dry clutch, if so then maybe late 70’s Margay chassis? Maybe late 80’s or early 90’s body work? I assume aluminum tanks are hiding under the body work. Body is not aerodynamic enough to run with a modern kart. If it is a 1″ axle, the axle is too flexible for use with modern sticky tires. Too old to be competitive, but maybe too young to be vintage because of the body work.
A whooped on but complete enduro kart from that era with aluminum tanks sells in the $600 to $700 range. But for a nice looking kart like that, value is in the eye of the beholder.
It’s a beautiful example of Americana vehicle culture. If someone buys it to part it out, there is a special place in hell reserved for them, plus the parts won’t be worth much. If you do get it, see if a road racing club will let you run it in in a road race in a vintage or a “run what you brung” class. Also run it with harder tires or it will hop like a bunny in the corners.