Kewl Go Kart barn find what's it worth

My Dad was a smart man ... I bugged him incessantly for a go-kart, so he got me one ... a steel-framed push cart with no provision for mounting an engine. He saw the things I did with my bicycles and figured (rightfully so) that I stood a good chance of killing myself in a motorized kart. By the time I figured out what I could do to get an engine in there I got a Honda ATC110 and forgot all about the kart.