I see numerous problems with this jersey...
1. Numbers and script "Dodgers" have unexplained and significant fraying. Looks like perhaps they were removed from another jersey and applied to this one.
2. The Jersey itself appears wrong for the 1965 Dodgers. Check out the attached SCP link, which shows a 1965 Koufax Flannel with good provenance...
https://catalog.scpauctions.com/1965...-LOT27629.aspx
The SCP jersey has "RAGLAN" (or diagonally cut) sleeves. The OP's jersey has a straight-cut sleeve. Big difference... and highly unlikely that the team would use both styles during the same season.
3. Also check out the embroidered script "Koufax 65" just below the Spalding Tag. The cursive script style is much different on the SCP Jersey than on the OP's jersey.
4. The positioning of the number 32 on the back is significantly higher on the SCP jersey, than on the OP's jersey.
So it looks to me as if someone may have taken a vintage/original Spalding Home Flannel, and added the Dodgers logo and number "32" to the front and back. Considering what Koufax Flannels sell for, it would be quite a lucrative endeavor for the "restorer".
In the spirit of giving the "benefit of the doubt", I suppose there's an off- chance that the Dodgers wore different jerseys for their 1965 Spring Training (and that this could be one of those). But that possibility seems a bit remote.
I know Dave G. gets paid to give his opinion, but as Rick stated above... it would be great if he could chime in with a few quick thoughts.