Ted Shackleford's Gary would certainly have a chance - you could tell he was quite a good athlete and Jock was decades past his prime - and I might favor him in a gentleman's match where they square up and play by the rules. He'd better not screw around, though, because as the old boxing wisdom goes and old Tom Owens found out, power is the last thing to go, and Jock certainly knew how to throw and take a punch and likely knew a ton of street-fighting tricks that Gary never would have learned. If he started off on that speech above without being fully poised for action, he might find himself looking up at the elevator lights before he got halfway through.
even without coming to blows, it'd be amazing, though, like an intense one-act play! Imagine more 'art' and less 'soap' than regular Dallas. Jim Davis wasn't the best at just kind of 'filler dialogue', but he could do intense pretty well (like the 'real power' scene with Bobby), as well as a certain type of sentimental, as with Ray in 'Fourth Son'.