You are both right, he was either very close or already had fallen to the Dark Side, then he found the Emperor.
Interesting - so Revan found the factory already in place on Nar Shadaa when he was the Dark Lord - it was part of his original quest to find the Infinite Empire's technology?
He was converted by the Emperor himself? I thought he just turned to the dark side over the course of the long and horrible Mandalorian Wars as a means to an end. If he somehow encountered the Emperor, surely he would've known something about the location of the true Sith, and yet KOTOR 2 suggests he had no idea where the true source of the Sith threat came from? Last we heard he set off into uncharted space to stop them?