An interesting matchup while it lasted. Kalambay would be elusive for a while. However, he neither had the power or speed to get Monzon's attention. Meanwhile, King Carlos would slowly but surely stalk Kalambay, clinching him relentlessly, and landing thudding jabs into the shorter man. Late in the bout Monzon finally ends it, courtesy of a powerful trombone right.
I see Carlos Monzon stalking Sumbu Kalambay for 5 rounds, firing his long left jab, meant to keep Kalambay off balance. Monzon begins to cut off the ring, countering all of Sumbu's punches. In round 6, Kalambay catches a hard right hand, and down goes Sumbu for the full ten count.
I think Kalambay can outbox Monzon. He'd have by far the best combination of boxing skill, defence and speed Monzon encountered.
Close encounter between the two, Carlos struggles until he finally figures him out. Dropping him late and stopping him. Monzon by 14 rd ko.