Jennifer, do you bother to take Australia and New Zealand as Japan, then?
If so, you need to dedicate a transport and at least one infantry to that cause already, before even considering Brazil. The infantry that you use there are usually pulled from an island that is not reachable within 1 turn to get to Asia anyway, so it’s misleading to count the cost of that infantry in your analysis. Therefore the total expenditure is 8 IPCs (the transport) to gain 3 IPCs of income for sure (AUS and NZE) and either 3 IPCs of income (Brazil) for a turn or two before the US retakes it, or at minimum the ability to distract the US from its purely atlantic campaign and the possibility of diverting to Madagascar (1 IPC which can theoretically be taken in the same turn Brazil would have). Once you take NZE, heading east to Brazil/Madagascar is probably the next best choice unless circumstances dictate otherwise.
If you DON’T take AUS/NZE, I have to ask why not? You are giving the UK 3 free IPCs per turn and costing the Axis 3 => net effect of 6 IPCs difference. Sure it requires the initial 8 IPC investment of the transport but that pays off in two turns easily. It’s especially potent if you are trying to threaten M84, since those are much needed IPCs that can swing the balance in your favor. Add to that the above possibilities of what to do with that transport afterwards and you can see it’s definitely not a wasted effort.