If its the Revell one, I think you would be lucky just to get it to float without major surgery on just about everything to make it light enough. Then there would be the problem of persuading it to float upright. Much of the plastic in the model, and therefore the weight, will be in the deck and superstructure parts, therefore above the waterline, therefore adding instability.
The numbers on the class say that at 1:300 scale, a 2000 ton ship will weigh about 3 oz. Not much to play with once you consider the weight of the plastic. As a comparison, a Revell Flower (about 1000 tons) at 1:72 weighs 6 lb in sailing trim.