Oh, are you not working on it anymore? Apologies for bothering you if so.
Anyways, here are two screenshots of the trial board (nikolai is normal bo2, takeo is your texture pack)
Looking at it again, I'm realizing that perhaps it's not so much that the bo3 textures are more pixellated, but rather that they are higher contrast (this is most easily seen by the lines in the cement. They're much darker in the bo3 textures), which makes the inherent pixellation more apparent?
(I'm really not very knowledgeable with this stuff lol)
Is there any particular reason you don't also use the mipmaps from the bo3 files? The Moire patterns created without them take away quite a bit from the experience.