school rank doesnt directly affect your UAI.
For example, an average student at James Ruse would always beat an average student at a 130 ranked school, due to the strong showing of james ruse' overall exam results, hence scaling everybody up.
If youre ranked first in everything but go to a non 200 school, you could still get a decent UAI, as the UAI you get depends on how you, yourself go.
Hope that helped.