You could bring a couple of mech infantry along with the tanks from west germany. These could act as soakers for the tanks.
If Japan takes Calcutta and India retakes it, does it go back as a normal capital and receive ipc’s like it did before (minus the reduced factory)?
Just FYI it also ejects any Allied control markers (so if the USA controlled Shan State because you did not have a capital at the time, as soon as you liberate, the USA marker is ejected and it returns to UK control).
This is true of Paris too, so it resets all blue areas back to French ownership upon liberation if they were “liberated” Allied at that time.