since N'zoth doesn't appear to be chained and completely free and the cause of Deathwings corruption, the Nightmare, The Nagas existence. Yeah I'd say a fully unleashed old god that had fought against the Pantheon of titans is as strong as a single Titan.
Infact he is so built up if N'zoth is anything but the final old god we face in the History of WoW it would be a let down. Currently 4 are known and there is said to be 5. Go figure.