You have a Robron Superdart someone has goobered up with the nerf bars and rear bumper. Robert Stanton worked for Mickey Rupp and bought all the kart stuff and tools when Mickey got out of them, Robert continues to build and sell Rupp kart stuff. The Superdart came out in '75 and is an A Bone modified for dirt oval racing.
The tip offs are the front porch, the bolt in floor pan & seat, and the narrower than usual steering hoop. It's late now and the only reason I'm up is the dogs wanted to go out. I will pm you tomorrow. That is a kart with potential as it appears to be in great shape. Most dirt karts that old have been beat to ****, yours looks great. It wouldn't take much to take it back to the way it was built.