He would land on his back. Unless he was blocked hardcore then he would almost land on his head. But the way he did it he would tuck his head, bend, tuck his legs, and actually his lead-leg (when standing) would whip around and come full-force at his opponent's face, lead-leg because it traveled the most distance and could build the most speed I imagine. And yeah it was his claim-to-fame when he was a fighter because no one else was even attempting anything like that on the platform.
The thing about full-contact Karate tournaments at that time and still to this day (though most of them are point-sparring because people suck) is that it was very dis-organized when push came to shove. It would seem all their skill would go out-the-window and they'd just flip out and launch dis-organized kicks and punches in kind of a panic when someone would get close. Some people did this very effectively though. Billy was one, Tokey was another, and then there was Keith Hirabayashi (a.k.a. Keith Cooke, who you'll most remember as Reptile in the first Mortal Kombat movie and Sub Zero in the second one, where he fought J.J. Perry who playes Scorpion who was a real TKD Champ), Robin Shou was actually a pretty fierce Competitor before going into Film as well, he used to get DQ'ed a lot for being overly rough.
But a lot of the best stuff from the 80's had long-since been forgotten. Though there were some really god fighters about, it's damn-near impossible to find the fights that went on now.