George spent only the latter half of 1963 with the O's, going 0-1 with a 5.40 ERA over 16 games, but continued to pitch in their farm system until the middle of the 1964 season. His longevity helped him to achieve the all-time minor league strikeout record with 3,175 and he also holds the Mexican League shutouts record with 55. He was even posthumously elected to the Salon de la Fama (Mexican Hall of Fame) in 1999 for his accomplishments south of the border.
So why are copies of George's autograph so scarce? From what I understand, it's because he rarely-to-never returned to the U.S. from Mexico after he began pitching there in 1973. At least one other Orioles collector that I've spoke with even said something along the lines that Brunet dropped off the map in the years after he stopped pitching until shortly before his death in Mexico in 1991. He was only 56 when he passed away. I've seen a few signed Brunet cards for sale but never have had the timing or luck to add one to my collection.
He was featured on a 1964 Topps card as an Oriole (although not in an Orioles uniform, I don't know who ever wore collared shirts under their jersey, but I'm guessing it was the Houston Colt .45s), so theoretically, there might be a few signed copies of that card out there somewhere. He was also included as an Oriole in the 1991 Crown set that came out shortly before he died, but it's pretty unlikely that any of those cards made it to him to sign in Mexico in the months between their release and his death. RIP George.