According to http://www.ketogenic-diet-resource.com, an ounce of broiled sirloin contains 8 grams of protein. So six ounces of steak would give you 48 grams of protein. Now six ounces = 170.45 grams, so your steak would be giving you 48 grams of protein and 122.45 of fat, or 192 calories and 1102 calories, respectively. Twenty grams of carbohydrate, the limit we recommend for getting into ketosis, is 80 calories, so there’s 192 + 1102 + 80 = 1374 calories of your daily intake already accounted for. If you wanted to hit 2000 calories, then you would only need to eat another 626 calories, or 69 grams, or about 2-1/2 ounces, of fat.
Seems eminently doable to me. And note, by the way, that the percentages work out to 9.6% of your calories in protein, 86.4% in fat, and 4% in carbohydrate.
But you don’t really need to worry about percentages. Start with this: if you keep your carbohydrate intake under 20 g, you are virtually guaranteed to go into ketosis, especially if you keep your protein intake to 0.8 to 1.5 g per kg of lean body mass. Then be sure to get enough fat so that you feel satisfied. That’s it. Don’t worry about how many calories that is, just be sure to get enough fat to satiate you. Let your body tell you when you’ve eaten enough. And stick with the ketogenic way of eating long enough (several weeks) to be sure that your body makes the transition from being carb-adapted to being fat-adapted. You may be surprised by the results.