Brazil did not use Mausers before 1894, and most of those were removed from service before WW2 so they may not have been rebarreled. Model 1907 was the first Mauser Brazil issued (M98 variant).
Before Mausers, many South American armies used Comblain rilfes, but I doubt even the most sun-addled infantryman would opt to fire a Comblain rebarreled for 30-06. I have seen Remington Rolling Blocks chambered in 7X57 and 30-06, but I am not sure if Brazil had any of them in their arsenal.
A picture is worth a thousand words.