I always attack Japan in China on UK Pac 2. This reopens the burma route (as the Japanese have way too limited ground forces) and keeps china in play. China is really more important then most of the players think. I find them very strong, especially against those scattered Japanese forces. The only problem is their airforce but every japanese unit you can take out on the mainland, is a huge win.
Crazy thing about the Japanese air force and Chinese units is this, the latter just needs to keep those precious stacks out of their range. Pull back, retreat. Advance when the time is right. A smart Chinese players does this, and makes the Japanese player really invest their time in the Chinese hinterland, splitting their options.
Best strategy for the Chinese is to play exactly like the Russians: Turtle up and keep one step away from the units trying to take them out. Each round you’ll be able to add 2-3 Inf to your big starting stack. Once Japan attacks the UK or Anzac, you’re free to start marching towards either A: Burma Road to reclaim it or B: The valuable territories the Japanese start with in the north.
Both cases make Japan invest more deeply into taking China than it wants to, while buying time until India can help you retake the Burma Road. Don’t play foolish with your big starting stack, protect it until the Japanese are too thin or they’ve invested too much in China (which is an IPC sink if Japan doesn’t get it early).