There's a simple tool you can make to lap the lug seats. However, the tap dug in some "threads" that are pretty deep. The amount of material you would need to remove will simply increase the amount of unsupported case head. Why would you want to do that? In this case, since you are getting it rehardend, a small amount of lug lapping beforehand would break any edges present. The small amount of "threading" just happens to be inline with the ejector slot in the top bolt lug. Leave it be as that area is unsupported anyway.