I’m sure the Brazil/Africa concept has been talked about before, but I wouldn’t suggest it. The main reason being is that it takes too long for the japanese transports to reach South Africa. Think about it, from Pearl Harbor, it takes 3 turns to reach South Africa. However, you must still wait an extra turn to place the IC because of the “no new IC on newly conquered territory” rule. Then you have to wait another turn to actually build units from it. This takes 5 turns (well, 6 if you count J1) for you to start producing any units from it. Then off course you have to move those inf from South Africa all the way up to North Africa, where most of the fighting should take place. Overall, I wouldn’t suggest it for obvious time and IPC concerns. Remember I’ll take time for those transports you sent out to Africa to return to Japan along with the 15 IPCs to buy a IC.
Key point, if you want to help the Germans out in Africa, I suggest setting up a convoy route from India to Egypt for a constant stream of units. Chances are you can reinforce the Germans quicker without wasting an IC to do it.