Banknotes from Brazil during that era had actual handsigned signatures from bank/treasury officials to validate them, rather than the printed signatures that every other country used in the 20th century through today.
I am not aware if there is a resource to identify those officials' signatures.
In any case, that is not a celebrity autograph on your banknote.
One friend from Brazil gave me some info on the signed bill. His text follows, in quotes:
“Well, I found out that these cruzeiros Bill were issued in 1956 and, by that time, some governmental authority from Central Bank use to autograph some Bills. The one who is in the stamp of The Bill ( ) Is NOT THE ONE WHO SIGNED THE BILL
“Other thing: these Bills were refundable in Gold by that time...like US Dollar till Nixon's presidency.”