Hrmm 50lbs in almost 15weeks correct? Thats about 3 lbs a week. A tough stretch but may be obtainable if your work ethic is solid and diet/training/cardio is on point. I think 25-30 is def obtainable
I'd look into CKD or The anabolic diet. Throw in a few 14day runs of the velocity diet and I think you could get close.