Generally speaking allies like to stage from queensland already because it is in range of the dutch islands… although I have noticed some players who stage from hawaii or caroline, but I like that because it is make calcutta super easy.
ANZAC take is rough against pacific heavy usa players and/or if anzac is fighter happy.
Everybody is big on the Calcutta crush although I’ve never seen it successfully pulled off in anyone of my group games.
Like you said it is high risk and high reward. It requires J1 or J2 DOW, because lowering uk pac income is so critical to the success of japan. It also requires an airbase off of kwangsi and sometimes a naval base to blast off and hit india at that critical moment.
you also have to hold shan state or yunnan at some point… so if china stacks up szechwan round 1… you need all your air in kwangsi ready to hit that, because you do not want that to get to yunnan or burma.
Calcutta is not for everybody, it is a gambit, though you can usually get 70-90% odds, what is left is half to a few of all your air units, so
I recommend just getting the money and maintaining your position on the board, even players that plan Calcutta and get everything setup and ready to go end up not pulling the trigger sometimes.
IF you do J3 DOW and still want to have fun in calcutta. delay your J2 airbase buy, get all transports and men. position fleets right over british islands you wish to grab. J3 DOW. drop airbase and naval on kwangsi.
from there you blast off and hit india. problem is holding yunnan or shan state on that round, which is why I like J2 DOW, I plan for it with the airbase on j2 and the transport j1 buy islands out of the way etc etc…. units coming down etc I prep for it indeed, but I don’t have a binding resolution with myself to do it (basically it is fun and if i got the odds I am going in).