Its a ridiculously tough fight for Ali. Joe was so fast, powerful and accurate. But the fight films show that he had tremendous issues with movers, even when he was young......
Whenever I watch his matches with Farr, Conn, or Walcott I shudder at the thought of what prime Ali would have done. In Ali you have someone who is taller, heavier, faster of hand and foot, with a telescopic reach and one of the best abilities to absorb punches ever. To beat prime Ali you need ridiculous pressure and workrate, but Louis was more of a stalker. Its a nasty style matchup for him.
I'd expect a decision win for Ali. But Ali would have to be on his bike much of the night!
I do favour prime Louis over several versions of Clay/Ali. I'd favour him over the 1960-1963 Ali, who just wasn't quite poilished enough before Liston. I'd also favour him over the 1970-1971 Ali who met Quarry, Bonavena and Frazier.......and also every version of Ali post Thrilla in Manilla 1975 (though the Ali that met Norton 3 & Shavers would still offer stern resistance).