Curtiss Warhawk - the plane renowned for it's duty flights in China with the Flying Tigers squadron. The Warhawk was used by most Allied powers during World War II, and remained in frontline service until the end of the war.
Chinese Stealth Tech- many think China borrowed fighter technology. I also think it would be foolish not to use proven ideas. Plus if your designs can be taken the only main advantages are strategy and training. This where the majors have the edge.