Heritage also featured a 1965 Koufax Home Flannel. But this one was made by Tim McAuliffe (not Spalding). It also has the correct Raglan (Diagonal) Sleeves, as appears to be the case for
all mid '60s Dodgers Flannels...
The Heritage Jersey realized a similarly enormous price, so make of it what you will....
https://sports.ha.com/itm/baseball-c...a/7105-82121.s
To the OP...
Given the obvious concerns with this jersey, I would recommend the following. Unbutton it, and hold it up to a bright light. Look at the number 32 on the back (from the inside) with the bright light directly behind the jersey. Do you see any evidence of prior stitching or embroidery? If so, then you've got your answer. If not, then perhaps consider sending it to either Dave Grob or Mears for further authentication. Hope this is helpful, and best of luck!