If he caught up within two boat lengths out to your side, you had full luffing rights, and could take him head to wind, if outside two lengths you would be limited to proper course, but I think it's based on the current wind, not a future wind. But I'm not sure, if you really think that you will finish faster sailing higher the the mark planning on a header, and would do it anyhow if the other boat wasn't there, he might just have to suck it up as windward boat and take your stern, as long as your not right at the mark and trying to go around by yourself.