I say Orochimaru wins this.
Kisame loses a very important advantage - Kisame has nothing to absorb.
Orochimaru doesn't use chakra-based techniques. He fights using snakes and other physical forms of combat. Kisame's main advantage when fighting opponents is stealing their chakra to prevent himself from getting tired. In Orochimaru's case Kisame has nothing to absorb. Can Kisame absorb the chakra out of Orochimaru's snakes? I don't think so.
Orochimaru also has a counter for Samehada as well because Orochimaru is also a fairly well-rounded swordsman. His Sword of Kusanagi is sharp enough to damage Enma who is as hard as diamonds. It would wreck havoc on Samehada.
Orochimaru takes this with high difficulty