Hofner did offer their guitars as left-handed to factory-order, although these are rare.
Note the Type 510 pickup fitted. This is unusual for a 1966/67 guitar supplied to Selmer, as Selmer guitars were usually fitted with the most up-to-date pickups. Indeed, the Selmer 1966 catalogue shows the Senator fitted with the Type 511 "Staple" pickup.
However, the 510 was fitted to budget archtops and semis for the European and US markets up to the late 1960's.
The neck/body joint has been marked up to stress that this is a left-handed Senator during the guitar's assembly stage. Usually, just a simple numerical code was used on the end of the neck and the body recess to match the correct neck up with the correct body. (Body and neck spraying were carried out independently before assembly.)