Hey, dude. I've been trying to find your original SFM port of this Moxxi model with the cell shaded tits, but I can only find the Gmod port. https://www.deviantart.com/rastifan/art/SYSK-s-Nude-Moxxi-With-Bodygroups-Release-For-GMod-544162977
Oh wow that's a blast from the past. Fucking CBBE era. Dark days indeed.
If anywhere, she'll be in the Everything 2021 dump in the Content Dumps section of my Assets page. But honestly that model is so old I can't guarantee the textures are even there. Though I imagine the gmod version's textures would work fine.
Though that being said, the gmod version should work fine in SFM anyways. It's not the original but, it's better than nothing, right? I'd check the Everything 2021 dump though, if you have the patience and the hard-drive space.