Coetzer was too tough for his own good, he took a thrashing from Bowe and Foreman, the White Buffalo was a boxer puncher who like to fight behind his jab I can see him outboxing Coetzer to a decision. I don't think it would be a slugfest.
I slightly favour Botha. As some have noted he's the better boxer and the harder puncher. However Coetzer is tougher, better conditioned and more active. Either could win really, either Botha with effective boxing or Coetzer tanking whatever Botha threw at him and outworking him.