That kart is cool! My first impression was that it was a factory kart or something bought from Sears, like this:
Can’t find another one like it, but that’s perhaps due to the fact that search engines suck now.
No need to restore or refurbish the whole thing at once, I’d stick a gas engine on there, provided of course it bolts up
the to the engine mount, grease the bearings, inflate the tires and so forth. Tires look fine although if they are tubeless and leak they might be past their expiration date. If tube-type tires, then patch the tubes, air up and go.
Get the kart running and operable first, then you can refurbish.