It is always worth looking really critically at the inside of the bore for corrosion and pits. The corrosion is similar in colour to the bore and so not all that obvioius. My suggestion is to take a dental pick and lightly explore up and down the bore, letting the end of the pick glide along the bore. If it hooks into a pit, and loose corrosion falls out, then probe around until the corrosion stops falling out. You are not creating a hole, you already had one. You just need to find out how big in diameter and how deep it is. Generally, if the dental pick is hanging up, the bore is screwed, and it is unlike that you will be able to hone it. My advice is to sleeve it down, but that thread is tired, so enough said. But it will need sleeving one way or the other. It is best to find out what you are dealing with before you order parts.
Stephen