D ont count out the 300 straight 6 its a mighty torque engine and will take much abuse heck it was good enuff for buses and dump trucks!!I had 1 in my 77 f- 100 big mud tires, low gears ,I would let the air outa the tires ,put it in low and mash the gas to the floor the only time i let up was when I got to the other side of the mud, valves floatin all the way!!never had any probs at all with this motor!!!