Alexandrefernandes zPolyCombine unfortunately does not handle UVs.
A work around would be to use Maya's built-in PolyCombine - selecting the objects in the same order and then deleting history on the resulting mesh.
Then use a blendShape to drive that mesh with the result of the zPolyCombine.
This way, the performance should still be significantly better then using the built in PolyCombine per frame.
I hope this helps!