1991 Mitsubishi Galant Overheating damage

My engine was cold for 45 minutes, and I didn't notice it getting hot or overheating. Although I do remember smelling something odd through the air conditioner I had dismissed that as smells from the city and not from my car, and that was on a few occations. I don't know if it is relevant, but in about 15 minutes after starting my car this one time, it overheated. The gage was in the red and the engine was smoking. Unfortunately I was in an airport and it took a while for me to pull over. Once I did, I popped the let it cook and opened the radiator cap. I filled it with water, and the water pump seemed to be working because I could see flowing liquid when the engine was running. I drove it for a few miles and it held temperature well, Then it got hot fast again and I pulled over. This time I waited till it cooled and removed the thermostat, which was stuck closed. I replaced it as well as the lower radiator hose for fear it was leaking. This time when I started it up there was white steam coming out of the tail pipe. It didn't seem to be mixing with oil because it was clean when my hand was in front of it and produced no smell. Finally, my question. I took it to a mechanic and he said that the head was warped. He is estimating 1,500 dollars to replace it and another 500 and something for a new water pump. This seems high to me. Although with all the symptums I think it is possible that the diagnosis may be correct and make sense to me with my limited knowledge of cars, however, I feel like this is far more expensive and I am wondering if it is just the rare parts of my car?

Thank you for your time.