Re: To Lap or Machine that is the question?
The bolt lug faces would need to be lapped to mate the inside of the receiver. But to true the receiver, it has to be done on a lathe. (Unless you have access to the proper hand jigs and tools and the experience to use it correctly.)
The receiver tube should be mounted in a fixture and trued around the hole in the middle where the bolt functions. All dimensions should be either aligned parallel or perpendicular to that long axis of the receiver. Unless you, or a friend, have some machining experience, this might be a good time to hire this one out. A miss-step on the receiver can cause a lot of headaches down the road.
Whether it is done completely by hand with the proper jigs and tooling or done in a lathe I guess depends on who the person is doing it and what equipment they have on hand. But before I let someone else work on a rifle of mine I would want to talk to several people that have rifles they have worked on. I would want to know in my mind that this person is the real McCoy. I don’t want anyone to TRY to learn anything on a rifle of mine. Most good rifle smiths will give you a guarantee of ½” at 100 yards or better. Some of the real good ones will guarantee ¼” if you replace the barrel at the same time.
Good luck in your choices ahead.