There are plenty of high calorie MRPs that have similar calorie and protein content as milk, with considerably less fat. In all honesty they are much more economical.
In terms of protein you need to add chicken breasts, lean red meats, eggs, fish. Carbohydrate wise fruits, vegetables, oatmeal, rice, and certain breads and pastas (These are worthwhile carbs).
Increasing calories should be easy simply for the fact that you are really only eating one thing at each meal. If you eat two cans of tuna stick a couple pieces of bread with it. If you eat shrimp, make sure you are eating rice with it. At the Italian buffet find some meat.