Dirty as fuck Black/Thrash from Brazil!

Genocídio's self-titled EP from 1987 is probably exactly what you're looking for. Very much in the vein of early Sarcofago and Holocausto. Filthy as the fucking bowels of hell.

Vulcano is a must too, but I'd be surprised if you hadn't heard them.
 
Ratos de Porao is sort of punk, but I don't like punk and I like it. More like thrash, almost. Check out songs like Sofrer, Pedro, Terra de Carnavale, Dificile de Entender... probably some type-Os in there.. the band sings about topics like Sepultura would, but more political.