Do we need a new engine?

While my grandson was driving the car, it just quit. He got it off the road and tried to start it and it would turn over but not start. I had it towed to a garage and the mechanic there said that the head seized up and timing belt was broken. He said there was no oil up on top of the head and where the cam is, it was black like no oil had been there. He says bottom of engine turns over. He thinks we need a new engine because if we fixed the top, we would not know if the bottom was damaged.
Please give me your thoughts. Thank you.