The donuts are round with a metal insert. If you have them they will be easy to recognize. Sometimes you can re-use the old ones if they are in good shape. You really need them as there is no other way to fit the x pipe.
What? He milled the crack out? I don't understand, if he said it would cause a leak. When I did my head gaskets, there were small cracks between a few of the valves. I removed the valves and looked at them close and the cracks were quit shallow. I decided to re-use the heads. That was a year ago...