I also upload the screen shot of emp_demigryph_chariot_01.rigid_model_v2 file opened in Hex Editor:
As your retexturing guide wrote, I replace the string "chs_gorebeast" with "emp_demigryph" (keep same string length) in diffuse & specular respectively. There are 4 string folders need to be replaced for each dds file location.
Spoiler Alert, click show to read: