The others are right. When you come to sell the car, who would want to buy a 200 / 200 Cup "cross breed"? Also there is a significant risk that adding bits/ parts and messing around with the car would reduce the car's reliability / increase the number of problems you could have with it. My advice would be not to accept the car. Don't second guess yourself, you obviously wanted a cup chassis and now doubts are creeping in - refuse it, and get what you wanted.