For the long run, it's generally a better idea to take two of the eight required cities for the UHV from Corea & Japan. Mostly because it's the logical thing to do and that those city sites help out your empire immensely. I've always interpreted the 1st UHV condition for China as a subtle context to conquer your neighbors, much like how the "be first in score" condition for Japan is a subtle context to conquer your neighbors (along with the not-so-subtle Greater Empire of Japan goal).
And wait, what? Discovering Paper founded you Catholicism?
That can't be right. Don't you mean Theology?
I believe you can go through Theology to get to Paper