This is the first time I have looked at this signer. From what I just read and saw, the OP seems atypical, perhaps missing a letter("d"?) which seems odd for an older signature, and overall legible and possibly strange from the comparisons I made. What do others think? Looking to learn :)
I find Koufax signatures very difficult to authenticate, as his older signatures were consistent, but his later ones are all over the place. This one has a PSA QO as "likely genuine" but I would not want to own it.