I think the issue is that the school wants her to read "in her range", which would be 790-940L, right?
If she likes fantasy Patricia Wrede has a few clean adventures within that span, starting with Dealing with Dragons (why does the lexile level of the following three books in the series drop down???).
Tamora Pierce is a bit more teenage oriented (and after re-reading the first Alanna book yesterday night I ruled it out for my son in the near future) and some of the series are in her range. The Circle books and the Trickster *might* be OK, IIRC there is little sex but (like most fantasies) quite a bit of death and mayhem.
Some of the Heinlein juveniles are in her range, but you'll need to make sure she doesn't slip into the other stuff.
Although in my experience young kids are very good at ignoring the weird stuff if it is way out there for them. It gets to be problematic when it gets closer (but not close enough) to age appropriate (reason why reading Vian's Heartsnatcher at 9 didn't scar me for life, but late Heinlein at 13... was a lot iffier).
For your son... It gets difficult to find fun stuff in that range. If he likes fantasy and hasn't read it yet the Odyssey (the real Homer) is in his range, and it was a big favorite of mine as a child. The Illyad was very disappointing after that.
