Wow Utelore - I really do not know why you want to go here?????
You would have nothing in Isolation, if China were to dream of going this route, then have no doubt, a lot of skillfull preceeding diplomacy, would leave the opposition, far more Isolated than they would wish. Further, you can rest assured China would not embark on such a adventure alone.
My best guess would be an Oil Assets conflict on three fronts (Japan, Western Forces in Central Asia and Iran) conducted through the Shanghai C O and essentially a Sino-Russian Joint Venture, for which the Russian Price would be Chinese assistance in the Ukraine,the Caucases (especially Azerbyjan) the Balkans and possibly the Balts.
I go for this as this would be primarily a Land War with any operations against Japan led primarily by the Russians with their Navy and Airforce - China supporting.
So what would the land war look like? Well, at the height of WW2, Stalin managed to put 30% of the Soviet Union into Combat Units. Apply that formula to China and you get a figure of 390 Million troops. I give you this just so any lesser massive figure that gets mentioned is seen in context.
I do not think there is any doubt about China;s ability to equip a very large army to a reasonable standard - even if only motorised light Infantry, with AK's and an array of SAM and ATGM shoulder pad systems, motors etc. I say this to correct any notions of a Korean War type scenario - one bolt rifle per squad or platoon etc.
You would have a proportion being equipped to full mechanised level (T96 standard etc) plus you then have the Professional Army. Add to that the technological resources, equippment and forces of the Russians etc.
Do I really need to go further, forget Clancy and his M'bation fantasies, I doubt if the West would have enough HI Tech surveillence, smart weapons etc to do more than simply raise casualties and slow down the advance. Just because you can see a swarm of Wasps approaching on a clear day, does not mean they are going to sting any less when they catch you - unless of course you are able to run and hide!
Happily however, as the Chinese are more concerned with taking the nect 50 years to become avery rich and developed Superpower. I would say that the chance of anything like this happening are nearly as slim as me being elected President of the United States.