The Pigeon guns in CEO-, DEO-, and EEO-Grade and the FE-Grade Trap Gun were catalogued as straight grip guns. However, any grade from A to EEO could be ordered with a straight grip at one time or another. I don't know of any grip options for the various K-grade guns (aka Model 1900).

These K-grade guns were made from 102 to 112 years ago, so many things could have been done to one since then. Until we see some pictures of the gun in question this is all an exercise in futility. I'll never say never, but I'm 99.9 % sure no Remington Hammerless Double Barrel Shotgun ever left Ilion with a vent rib, and no K-/KE-/KD-/KED-grade ever left Ilion with engraving.