A great victory has been won,
half a million men are gone...
Great job. Hopefully the Chinese units will be useful in combat.
Depends on how fast can you conquer them. I think India could be crushed relatively quickly - you can lure the British to establish a front there, and then land forces behind them, encircle, and destroy them. Just don't fight in the jungle, that's... not healthy
Since you have a land connection, you can use the Chinese units as cannon fodder. If India falls, you'll have another powerful puppet to use against the Allies, and it will make it easier to assist the Germans in the Middle East.
On the other hand, there is the danger of overextension when you need to focus on the Pacific, so invading Australia is a good plan too. Well, the decision is yours, as always