Hi Steve, I enjoyed your story in the TBM magazine.
I just ‘eyeball’ the curve and shape it with a rasp and a file. There is about 1/8″ drop to the curve front and back. I use a 4-way rasp at first because it has a smooth edge and I won’t dig into the back for removing the bulk and then switch to a fairly coarse file to square up the back corner. After that I use a square cornered piece of Walnut and sandpaper to finish.
On Hickory it takes about 45 minutes to do.