As this appears to be on separate tickets official MCT times do not apply. You potentially may have issues with the first airline when it comes to either valid visa/exemption as they will only see the one flight and some are stubborn about separate flights. Luggage may/most likely will not be ticketed through to LAX as many airlines do not check through luggage on separate tickets.
For me personally, involving Chinese airports I wouldn't go for less than 4 hours on separate tickets and be ready to rebook. You should look at the previsions of the return flight to LAX to see if it is changeable, when it has to be changed and any costs associated.

https://www.flyertalk.com/forum/chin...pudong-13.html is an existing thread about such things.