I know nothing about YC1, but definitely rank YCIII above YCII. YCIII is a p4p ATG, imo. Won and lost the WW world title, with impressive wins over Jackie Fields and Cerfino Garcia, it's his career above WW that really impresses. As a 5ft 6ins natural WW, he beat the bigger Billy Conn, Fred Apostoli, Gus Lesnevich and Mickey Walker in contests staged above his natural weight, which is extremely impressive.
All I know about YC1 is that he went a combined 37 rounds with Mysterious Billy Smith over two fights without Billy managing to get himself DQ’d, which is a singular feat. Corbett/Green must have been foulproof.
I'm not expert on the first Young Corbett myself, but from the research I've gathered he certainly seems to belong in the convo. He beat Mysterious Billy Smith as well as Dan Creedon
