"between a rock and a hard...wall"

Four courses later.. I think I may have a course of larger flagstone (from the garden divider wall) as the top and final course.
The least fun part was trying to fit and level the larger pieces for the stairs. Trial and error meant lifting and replacing those monsters 4 or 5 times each.. It was nice to have it finished though! Still need one or two stepping stones at the top of the stairs, but I'm waiting to fill the dirt in first and let it rain/settle.
You can see the drainage ditch* in the background. Hopefully this will divert a lot of the water that comes down the hill and relieve pressure/erosion for the wall itself.
*Runner-up for least fun part :)