Usually with ANZAC I will buy some land units and transports at first, when they are making little money. Then when they are making more later in the game, I buy mostly planes to send out and back up other Allies in tough spots.
There are a couple of more places ANZAC could possibly build an IC. If Kwangtung is captured by ANZAC while Calcutta is occupied by Japan, ANZAC could build an IC there, although they will lose it once Calcutta gets liberated.
Another technically possible place is Korea. Sure it is a reach but imagine this. The US has a large fleet controlling SZ6. Russia attacks Korea and loses the battle leaving only 1 Japanese Infantry. ANZAC happens to have a transport or two in range and lands some troops in Korea, kills that lonely Japanese infantry and controls Korea now. If Japan doesn’t have a counterattack force stationed in Manchuria, next round ANZAC could build an IC right there in Korea. Then perhaps they could crank out 3 bombers each round to plaster Japan’s facilities.