Work to be done:
Create an index for the 526 MARC fields
Add range searching to advanced search in OPAC and Staff on new index
Seeking Cosponsors here: http://devs.bywatersolutions.com/projects/add-search-accelerated-reading-level-range/
bug 20078 has some sample jQuery to add the serach filters to advanced search.
*** This bug has been marked as a duplicate of bug 20078 ***