Getting old. Sold the ranch. Sold the tractors. Moved back to the city.
The slab for my shop is 24x42 ft and sits on a slope with about 8" drop along the 42ft side. Here are some photos of the construction.
My contractor is a pro. There was no excavating except for the footings and scraping the top 3-4" of turf off the jobsite. The slab was leveled by setting the top of the forms level. You really don't want to excavate the native soil unless absolutely necessary.