Really depend on which country China sell their weapon to and the condition of weapon.
Of course one can mask the true capability of thier own weapon and still keep secret of their own. However, you always need to consider why people want to buy your weapon in the first place. If you change to much and put too many off the shelve technology or using a whole foreign parts to put it to the watered down version of Chinese weapon. You may hurt business.
When one build a weapon, you build with indigenous technology in mind, you will enconunter competibility issue when you put a foreign parts on what it supposed to be an indigenous technology. That the dilenma Chinese facing when they try to push their weapon on international market.