Eddie was not a particularly large guy and Coetzee was. To beat Coetzee usually you had to be his size with a big punch and an engine to push him to gassing out. I think Coetzee would be patient with Eddie, look for the openings and eventually land his crushing right hand to set up the finish.
Sonny Liston had 15 pounds on Machen but Eddie lasted the full 12 and had a few moments, fighting one-handed due to a ligament injury to his right arm. I could see Coetzee winning, but not by stoppage.
Machen fought a safety first fight against Sonny,imo. We saw what a big right hand puncher could do to an engaged Machen,I think it happens again against the SouthAfrican.