That seems perfectly reasonable as regards the riflemen. However the figures with support weapons in the other metal packs all appear to be wearing tunics, presumably the same type M1941, aka Parsons - as in the plastic set, which makes them inappropriate for the Pacific theatre as far as I can see.
A range of Brazilians would be good to see, though I can’t avoid picturing them in yellow shirts with their names on the back, mostly ending -inho.
Yeah, you're on your own if you want support weapons, although you could probably do some snipping and filing to the existing range or maybe repurpose support weapons from other folk's USMC ranges. That said if you are doing say Buna/Gona or the fighting on Bougainville, the nature of the terrain means you are unlikely to see much more than a .30 cal in action, on board.
If you want an officer, again you'll need to find your own but there are sufficient riflemen/ BAR/ SMG types to fill out a platoon.
Personally speaking, I paint all my Brazilians in red and black*.

I don't need to add a dimunitive to their names, as I can just get up from my painting table, walk the length of the house and tell my son to stop shouting at his on-line shooter game. 'Jorginho Pare! STFU!'
* I actually do have a force of Tupi that are mostly painted in red and black.