Just for the record;
last generation 5.4L= 300HP, 365 ft lbs torque
Last generation 6.8L= 362HP, 457 ft lbs torque
The 5.4L coupled with a 4.10 rear would be rated at 10k or more. My own experience with both motors is the 6.8L could hold speed in small hills without downshifting but the 5.4L liked to downshift and needed a little more rpm to stay in the sweet spot. The 6.8L can cruise on flat ground all day long at 2k rpm at 65 mph but the 5.4L needed 2500 or so to stay in the power band. Both are very good motors with a well matched load.