Kallie may be a bit overrated here, only one he knocked out with that "wild right" was a wading in wide open Duane Bobick. I did see 3 or 4 rounds of his 10 round loss to Gerrie Coetzee, from what i saw I give Knoetze the edge, Funny how South Africa had two world contenders at the same time. JOHN TATE completely ruined and tamed the "one trick pony" and Kallie was never the same monster after that fight.
1978? Lyle only had one fight that year, a TKO 7 against 7-4 (3) Horace Robinson. In 77 he struggled with Joe Bugner and Stan Ward, and in 79 he would struggle with Scott LeDoux and get kayoed by 10-4 (7) Lynn Ball. Meanwhile, Knoetze was scoring early stoppages against Richard Dunn, Duane Bobick, and Bill Sharkey. I've got to go with Knoetze by KO.
I remember Lyle as being better at that time. Obviously, if that's not the case then Knoetze would likely win.