From: St. Louis
This isn't entirely cogent, but generally, anywhere important on or near the front line or any isolated island, I try to get 10x the supply requirement. If you are the Allied player, there is nowhere on earth that you cannot meet that target. In your case though, I recommend you dump supplies in Rangoon til you reach at least 5x requirements, then see how things go. If you don't have a lot of stuff in Rangoon (ships, planes, troops) you need to go to at least 10x (imo) if you intend to keep Mandalay in supply. Transports and bombers are for emergencies or for troops deep in undeveloped roadless territory. I need to clarify that, air transport is always a good idea when you're having supply problems, but usually it's most effective if it goes directly to troops in great need. Usually the amount they can leave at airbases is a tiny fraction of the overall requirement and simply gets lost in the numbers. However, landing supplies at a small base that has an airstrip should be more efficient than air dropping the supplies.
But yes, if you want to invade India through Burma, you will experience supply difficulties equal to or greater than they will when they move to take Burma back. If you can take Akyab and dump supplies by sea there, that will help alot.