Just investigate the availability of a thicker head gasket. Plus the corrective factor it gives. It may even be possible to have the area of the surface built and only a very small cut overall made.

There are automotive machine shops. Plus there are the shops that do what is needed for average auto machine shops. In your case the thicker head gasket will probably do.

When something used to be tricky. I sent my work to the shop that does the exotic auto machine work for all of Canada..

What is even stranger is they were also cheap including shipping in those days. Anything they did was done properly and you could rely on it or they would not touch it. They are located in Montreal Canada about 6-700 miles from me. Building things up and restoring them where run if the mill for them. Some cars parts are just too expensive new to not have this done.

For example although I am not certain. They would possibly heat that head and pull the warped area down to a usable tollerance. Then mill the head.

My suspicion is you will have at least several shops in America that have this level of function. I think the reason they do not price gouge is the vast majority of work they do comes from other machine shops. Or exotic car dealers back shops.

Last is I might carefully clean up the area you are dealing with to get a better reading. There is a lot of junk on that surface.