I found this "rolling" kart, which has a frame, wheels, steering and braking installed. It looks pretty beat up, but it's dead cheap. The motor is missing but that is a good thing, I don't need it anyway. Here's some pictures of the kart.
Here's a close-up of the hydraulic brake on the kart:
Before even thinking about mounting new gear to such a kart, there's a first few obvious jobs that need to be done. We'll have to take apart the frame, clean it up, sand it down, repaint it, put the kart back together and fix stuff that needs fixing to get it rolling again. We'll then see what to do next.
I'll be checking it out on Friday. I hope it fits in the car, it looks like a great base to start the build from.