It depends on the leveling kit used and the size of your rear blocks.
A 3"-3.5" leveling kit will sit level with the factory 4in blocks(really measure closer to 3 3/4")
An add-a leaf kit or a 2"-2.5" leveling kit would look good with the shorter blocks from Ford.
I have the Fabtech 3.5in hangers in the front with 5 in straight cut blocks in the rear. Basically it is a 4 inch kit without changing the load capacity or ride quality of the Stock suspension. I think it looks good too. Overall, it sits a little higher in the backend but it is less than an inch so Im not worried about it. If I had the factory snowplow springs in the front, my truck would probably sit perfectly level.