Use C 16NZ again?

Hi guys, a few days ago I broke up my C 16NZ engine with a friend of mine, because we wanted to change the cylinder head gasket, because he lost water. When we had disassembled the engine, we also found the place where the ZKD was broken. Unfortunately we saw something not so pleasant then. 🙁 On all 4 cylinders are about 3-5 vertical bars, of which 2 are so deep that you notice them with your finger and stick with the nail in it. The Freun d from me, the car mechanic, said that he must have run hot and therefore the bars come. He then meant that it is actually a motor damage and I should get a replacement motor. I am looking for it, but unfortunately find nothing clever in my vicinity and if then only very expensive. The buddy of mine then meant that one could plan the head and assemble it again. He means that it can be that he can run then 2 years until problems can be solved. ngen or even after 2 months problems occur. I am not sure now what I should do ?!? The engine ran about 160tkm and actually always handled him quite carefully and Oel did not consume any. Did the car actually want to drive only 1.5 years. Hope you can help me further. Thank you