it's an interesting idea to play with that these could technically just be thrown into the psp version.
they would work. The question is at which point the psp chokes on itself. Considering the current state of it (there are slowdowns when 3d is involved) its propably a bad idea to toy with this too much.
however, it's a good thing that the hi-res sources are available, so some of the more badly converted textures can be redone.
even though it's a huge load of manual work to rearrange the textures one by one since their layout doesn't match (there's 288 files, containing some 300++ textures), redoing them as 256 colors (0% more strain to the engine) is an idea im seriously considering of attempting to pull of.
on the other hand.... we could always go 200% more retro and use this: