Yes, Largebore. The easiest way to tell is the receiver at top of body for the neck to fit in is the old, non-reinforced style. Very prone to cracking, so Selmer beefed it up a bit later, to the current design. Other tidbits, too, but serial that late and the neck thing are a dead give away.
Not much diff in tone between the Largebore and the earliest Supers. Later in the Super run, the bore tightened up some and the tone is a bit edgier, working into what became the 'BA sound'.
Nice horns, but with the tenors, you have to watch the tuning a bit. Got better in later models. I used to own a silver Largebore, serial 13,936 that I liked. Kinda wish I still had it, but couldn't afford to keep it and needed another horn, so off in trade it went.
I don't like the altos; earliest/best of the vintage altos for me is the SBA.