I'd slowly start to add some fuel, first in the way of extra protein and then add carbs/fat. Something like add 25g of protein and hold everything steady for a week and see what happens. If you gain < 2lbs, add another 10g of protein, 15g of carbs, 3g of fat to all days. Then keep reassessing every 2 weeks. If powerlifting or strength aspirations are in your future, then I think you'd be a good 165'er in 3-6 months, and a solid 181 within a year. Of course you could take another approach and throw GOMAD on top of what you're doing, get up to 200 or so and get really strong quickly, then cut to 181 or so.