Left front wheel/tire?
Live axle or one-wheel-drive?
Centrifugal clutch will run you around $50.
If the engine is in decent shape and it's geared decently, it's probably pretty quick with a centrifugal clutch. I'd lose the roll cage and forget seatbelts.
If it's as pictured and one-wheel-drive, you're looking at $350 to get it running, and then it's still one-wheel-drive (live axle is way better for traction and braking.)
Seriously, I'd be looking at Axton's kart above, that looks like a much better / great deal.