When I saw the movie, I wasn't familiar with the actors, so it was easy for me to imagine that they were Gatsby and Daisy, Nick and Tom. Karen Black, though, as Myrtle was too over the top for me.
There was also an A&E television version. I remember it as Paul Rudd as Gatsby, which would really have been miscasting, but actually he was Nick, and wasn't awful in the role. Gatsby was Toby Stephens, an English actor who maybe did have that "came from nowhere and shot to the top" quality. Daisy was Mira Sorvino -- not quite right.
Similarly, I think a younger (early X-Files era) David Duchovny would have made a terrific Gatsby. I could see him lurking, brooding in the shadows while a huge flapper party was in full swing on his estate. He's not stunningly handsome like Redford, but is far more cerebral, and would be the kind who could have convincingly dealt in the prohibition era underworld, while still cleaning up to participate in more genteel society.