Nice looking stave. I don't know much about Kentuck Coffee Wood however, I've heard mention of it several times as of late on this site. Some of the guys will chime in on this.
Curious though, what's wrong with the top ring? Aside from the sealer on top, does it violate any other rings? If not, I'd draw my bow out on the stave as is. The 4th ring is a bit thicker, yes. But, you are not limited to the thickest ring. Just a good ring. Why chance it, I say.