I have been working on another version of my ratings for test batsmen and bowlers since August. The most comprehensive yet, featuring a lot more criteria.
One thing that surprised me was that Courtney Walsh, so often forgotten, stands up against the best fast bowlers in all departments, whether that be overall average, away average, average vs. top opposition. And what astounded me was that his peak years were in his last 50 or so tests.
I think he is underrated by this forum and he would deserve a place in the alltime test bowlers top 20 imho.