Ignore the rest of the stuff on this post in this link. The second post has the chassis dimensions of a known good design.
http://www.ekartingnews.com/viewtopic.php?t=50307
Other than the basic layout, you may (SHOULD) measure the front end of a real kart and try to duplicate it. If not, the kart will not jack the weight of the kart to get the inside rear to lift (critical to turning with a live axle).
If you want to take a shortcut (and skip the complicated front end geometry), just copy the dimensions above and go with a single rear wheel as the ‘driver’ and let the other wheel spin freely. If both wheels are driven, the ‘live’ axle will cause the front to plow straight ahead when you turn the wheel (not fun at 40mph when you want to avoid things like curbs and cars)
ref: wheels and tires…most folks on here only have slicks to offer you. If you are gonna make this a ‘yard kart’ for dirt and grass, you may want to look at some snowblower tires.
Good luck and post pictures.