I think Ben can conceivably push Strong Guy past the point of what he can safely absorb before it takes to much of a strain on his heart. He's also the better more skilled fighter, but I think Guido will give him all he can handle, and could even steal a few wins if Ben isn't taking the fight seriously.
Ben would win. Better fighter and higher durability. Strong Guy could BFR Thing by picking him up and throwing him far away. That weak heart of his is really a drag for him. I don't understand why the creator gave him that kind of handicap!