I messed around with something similar a while back, and the trick that helped was extracting the texture files directly before editing. If the header’s giving you issues, double-check the byte alignment—some of those old PS2 models are picky. I learned a lot experimenting with models on https://skin.land/sell-skins/csgo/ , especially swapping UVs when matching textures from other sources. Worth a look if you’re stuck on mapping the edited skin properly.