Marciano signatures make me queasy. Plenty of good ones out there, but lots of bad ones to.
Including tons that have been authenticated by the major players and sold through major auction houses through the years.
Beware of typed/signed letters featuring Marciano. I can just picture Rocky flying from event to event in his post boxing years, dragging a typewriter with him, punching the keys in his down time to answer fan and journalist mail. All with great boxing content in them.
Archie Moore maybe (though he loved to actually write his letters out), but not Rocky.
I think one of Marciano's own brothers had a hand in lots of the bad autographs making it to market, once upon a time.