A stall around 2600 and a cam calling the lines of 216/230 would go great. Upping the compression to around 10.5:1 is a great idea. Mill the heads anduse 4.8L flattops. I wwouldn't expect 400hp out of a 5.3 however big off throttle torque is totally what you want and can get. If you plan on staying NA then a walbro 255 should be fine with 42lbs injectors and your good to go. Even with E85 I would imagine 42s and a 255 would be fine or maybe a 340 to be safe.