Well if you want to be different, go big or go home. Ford GAA. 18 liters that produces 1000 ft. lbs of torque AT IDLE. All aluminum DOHC engine designed and built in the 40's for air planes. Originally supposed to be a 12 cylinder but Ford chopped off 4 cylinders and put it in tanks for WWII
Or 7.3 swap.
Or 7.3 swap.