Looking at classic derailleurs but ignoring pre-parallelogram designs, the Suntour Superbe is the only one I could find with 23t max, Suntour Cyclone and V Luxe were 24t along with a few like Simplex Prestige, Huret Jubilee etc. Then skip to 26t for Campy Gran Sport, 980 and various Record, NR, SR models, Suntour Vx and Cyclone II, and Dura-Ace. Finally 28t for Shimano 600 and "bird" models.