Though I have no idea how this happened. I just finished a valve job on my car. I recommend either buying someone's used heads, checking it out yourself before installing, or fixing this valve guide and calling it a day. Without an explanation of how this happened I think there's less risk if you buy someone else's used heads. This is a sensitive area and you don't want to do this twice if you can avoid it.
If you're considering upgrading the engine only then go for the new heads. Go IPP.