Fly UK>FRANCE>PVG 3 nights (65 ish hours) SHA>CAN>Cambodia - Visa?

Hi we fly with Air France to Shanghai from the UK via Paris for a 3 night stay in Shanghai before departing from a different Shanghai airport via Guangzhou to then onward travel to Cambodia - total time in China is 70 hours - any idea if this 144 hour free transit will apply? It sounds like it should but the thought of getting to China and it not applying is slightly worrying! Thanks