People change over the course of their lives. This we know. Whether they change out of conviction or opportunism is very difficult to judge. Indeed, it's often a false dichotomy because overtime we come to believe what we find it convenient and expedient to believe. I think the operative question is what they do.People eventually do what's in their hearts. I'm from Arkansas, which was a lot like West Virginia (mining, union jobs, middle class, religious). I knew older men Byrd's age, some relatives. They were kind, gentle, intelligent, and ambitious. They won WWII. They grew up in a different age. They told racist jokes. They treated other races like a novelty, an oddity, almost like a afliction--like the handicapped. They grew up apart from other races, and as they realized (as they were being forced together by the Civil Rights laws) that other people were just that: people.
I think they were embarrassed by their former selves, and many went on to make great strides for the people they had ignored and ridiculed for so long. People do change. Some for the better. Others, like Trent Lott, don't. They just occasionally say something that tips you off to what they think, but long ago learned to not say in public.