stepping ahead to some degree, i suggest checking with the local geotech. i had a similar sized wall where the settlement analysis spit out something on the order of 6-8+" differential due to the fill induced settlement. even with substantial undercutting, we were still looking at 3-4". it's just a thought since it killed the wall idea on my project...turned in to a big slope and ate up part of the parking lot when the crest was moved back to provide the 2:1 from the toe.