[Frank Miller]

Here is what i have been told about this. Heads are really not milled or surface ground but simplay placed on a big belt sander to get them flat. The leading edge of the belt can be more aggressive so the head needs to be rotated.
If the above head is flat you could probably cc the chambers and run them as is with no problems.

A machinist told me that ideally a head should be surface ground. I'm guessing to do that you would need to square the head to the grinder which I assume could be a bit of a chore as there is no flat area opposite to rest it against. When I think too much I wonder how half the stuff out there is running, including mine.