I got a late start this morning, but got things rolling quickly. First I marked up all vertical boards for notch cutting, then I started checking the floor boards for level.
I quickly figured out that the slope of the floor was not a perfect mathematical slope, but had slight imperfections along the length of the rise. To accommodate for this, I put together a number of shims to have the concrete and wood slope edges match up. This is a good lesson learned that I'll carry over to a project I plan to undertake early this autumn.
I used my table saw to cut out notches in the vertical boards. First I sliced the notch areas as shown here.
The I used a slotted screwdriver and a hammer & chisel to clear out the notched areas of the vertical boards.
Once all the boards had been notched, I began assembly of the cabinet frame. I got enough done to test fit the shelves into the frame end and horizontal support wedges. Though incomplete, the frame and shelves are remarkably sturdy. I'm looking forward to resuming work tomorrow afternoon and getting more done.