My opinion, it depends on where and how they fight. In melee fighting I think Revan would win, but in Force Powers Naga would win. If they fought with armies, it could go either way. Revan is the smarter tactician but Naga is more powerful with full scale fighting. But Revan would most likely find some way to win this way. Naga seems pretty cowardly and reluctant to fight in single combat. Note that he didn't use any incredible magics in single fighting, all his abilities seemed to be a full scale only type thing (like Bastila's Battle Meditation). Being able to fling stars would also be useless unless he really wanted a stalemate. He instead relied on tricking his opponents which wouldn't work against Revan.
Revan had amazing potential (much like Anakin Skywalker), then he learned everything about the Jedi and everything about the Sith. He got even stronger without that knowledge and then he recovered it. So Darth Revan would be pretty resistant to Sith powers.
Also keep in mind that the Dark Side was spread too thin in Naga's time, shared among too many Lords. That's why all the greatest Sith Lords after that had only one other to share the power with. Exar Kun and Ulic Qel Droma, Darth Revan and Darth Malak, Darth Sidious and Darth Maul, etc. Naga, on the other hand, had been in competition with many many other Sith Lords so his the power would be spread too thin among them.
In conclusion, I think Darth Revan barely wins this one, mostly due to his saber wielding skills.
Well, the only reason I made that comment was because it says that in the new essential guide to characters under Darth Bane. That is why he makes the rule of two. Besides, Marka wanted Naga and Ludo to do the same thing I think, and later he did do that for Exar and Ulic. Its not the best argument, but it is a little interesting.