I think Buchanan wins this on points 9/10 times. Young Oscar would present problems but nothing Ken couldn't deal with over the course of 15.
Oscar was a beast at 135 against mostly average at best fighters and he had a great left hook...but when the comp stepped up a few notches like against Molina, it seemed he might not be so consistently destructive. Duran was a truly viscious puncher at 135 as well, and a much better two handed one, he was no where 'em down accumulation puncher.imo he had power about on par with a Wilfredo Gomez at the weight.If duran landed his best shots with consistency, the end was usualyl only a few rounds away at most.
Buchanan was a great champion, Oscar didnt fight anyone particularly good at 135. Oscar was very good but both him and you are overrated his power it wasnt that good, not as good as Duran and if you could avoid the left hook his right was pretty average at best Against boxers with excellent skills Oscar always got outboxed, see Whitaker/Quartey/Hopkins/Mayweather. They could make him miss and time him because he was quite predictable and his defense wasnt very good. Buchanon has the same type of skill here
This is essentially my train of thought also. As good, even great of an athlete as Oscar was, he could be mesmerized by a true ring general with the ability to box from a distance. I think Buchanan was good enough to take away the left hook, and tough enough to survive a round where he got clipped. However, the dissenters have inspired me to take a second look at Oscar at '35. Way to keep things civil everybody, I swear to God I need to just leave General alone and post here.