I'm planning on building a 28 x 42 garage, with two rows of split face block and walls on top of that?

The slab will be sitting on at least 12" on compacted sand, and up to 3 ft of sand, all which was laid last year and compacted. The slab will have 12 x 16 inch thickened edges and rest will be 4 to 6 , Not sure what i wont to go with yet.. Its about 1000 dollars difference between the two.. Rebar in footings, mesh in slab. Does this sound suffice?