IMO using real WWII rationale for China VS Japan does not compute in Axis and Allies because A&A does not use terrain. The #1 reason Japan did not take all of China in the real war was because of terrain. South West China is all mountains. North West China is dessert that is the second largest desert in the world. Also that desert is a nightmare scenario in winter. There is also this huge mountain chain coming up the west side of the China that is ignored.
If you want to change up the status quo in China in respect to Japan I would offer this. Using game mechanics in the game.
You use Impassible territories.
You put up a Impassible territory between Khazashistan and Novobirisk. The only way Japan can get into Russia then is to invade Timguska. So, you now force Japan to focus on the north which brings into play the Russia far east forces to resist them. It also forces Japan to diffuse their air power to the north. Which then brings up a choice Japan has to make. Go north with air power and leave India to build up and resist Japan.