I am not a Mauser expert but a few Googles brought up some information.
Brazil standardized on a Mauser rifle in 7x57 in 1908. They made a new purchase of 7mms from CZ in 1934. Brazil used no 8mms that I could tell. They got a lot of M1s from the US in WW II - there were Brazilian troops with us in Italy - and converted a lot of their bolt actions to .30-06 after the war. The stamp on yours 08/34.30 indicates it is one of those.
If yours is an 8mm it was rebarrelled from .30-06. IF. Be EXTREMELY careful before you try to shoot 8mm ammunition in this rifle.
Well you paid what you thought it was worth, didn't you?