The stamp is from the retouched die, 1st state, with fluorescent ink.  It must therefore come from plates 95-148.

The date in the postmark eliminates plates 113 to 148, leaving just plates 95 to 112.  The date suggests that the plate is closer to 112 than to 95.

Marler's description of design type R24 (plates 107-108) appears to fit.  Marler points out that many of the subjects on the two lower panes of plate 118 have a spur projecting outwards from the upper left corner.  The stamp in question has such a spur, so it likely comes from the LL or LR pane of plate 118.