When I saw the warriors in a museum in London( The Victoria and Albert, I think) the light levels were very low. I didn't have a camera but I doubt if 400 would have been enough. It would seem that in China natural light gets in which makes me wonder if the very low level of light in London was required( there was no natural light but the artificial light level on that basis could have been higher.

If taking the pics is a one-off, I'd be inclined to pack Fuji Neopan 1600 or Ilford D3200 just in case then load the appropriate film according to the readings you get.