IF I were you I would try a carb cycling diet. the idea is to consume more carbs on your training and conditioning days while having more protein and fats on your off days. EliteFTS has plenty of e-books and articles on the topic.
Start off by reading this:
If I were you this is how I would set it up:
High Days (3-4 on your Heavy Training Days)
Fats: Low as possible
Medium Days (Other Lifting/Conditioning days)
Low Days (Off Days)
Try to eat as clean as possible if you are looking to avoid too much fat gain.
Carbs: Oatmeal, Rice, Fruit, Vegetables, Yogurt
Protein: Eggs, Beef, Chicken, Turkey, Protein Powder
Fats: Natural Peanut Butter, Almonds, Olive Oil, Fish Oil, other nuts
After a few weeks adjust your diet depending on if your gaining enough weight or not.