I would favor Patterson as I’m guessing most would. But could Pastor have a chance? He went many rounds with a prime joe Louis and beat a good number of contenders. He was quick, crafty and hard to stop.
Bob did not have the kind of punch that would worry Floyd. He went 10 with Louis by fighting defensively. Sort of like Eddie Machen against Liston. Floyd's speed and sharpness would not be forgiving. I see Floyd stopping Bob in about 10 rounds.
Best-for-Best, I'd say Pastor could definitely make a good go of it and it wouldn't be too far-fetched to consider him standing a chance. But, as has already been mentioned, Pastor doesn't carry a deterrent and it is difficult to imagine him evading Patterson's wicked timing, counteroffensives and finishing ability, over the course.