I like LMR's skills to get him through here...but he would be giving away a fair bit physically, and against a guy who was as hard as you get at the weight. I think this is a very difficult match for both guys for different reasons...So I could see a fight being extremely close and even controversial, if I had to pick someone Id probably edge with Rodriguez.
Luis would probably have been motivated to avenge the brutality done to Benny Paret..and it would have been possible for him to have outslicked Gene, but the going would have been far more gruelling than it was against Rubin Carter, for instance.
From the films I've seen of Paret, it seemed that he always fought aggressively. Even when it did not favor him to do so...LMR would fight aggressively against bigger fighters (middleweights) too but he never fought with the recklessness of Paret. I think LMR would take a comfortable decision by flurrying quickly on the inside, then using those great legs to take him out of harm's way before Fullmer could retaliate. LMR was great at angles and so slick defensively. A great, great fighter.
Fullmer never claimed he liked "beating Paret up so bad". Paret's management kept throwing him in with consecutive tough fights and fights weren't stopped as quickly back then.