Big Block Fords are in a class of their own. In an application where raw torque is desirable there is no engine that is better suited. So how do you make a good thing better. Make it bigger. If you wish to limit your bore to 4.390 (.030 over) and keep the oil ring out of the pin hole (better oil control), then start with the Street Fighter 521. Easily capable of 550+ horsepower and torque in the same range. 521Street Fighter 4.390 bore - 4.300 stroke - Flat top piston - Cast steel crankshaft - CHP CNC Beam forged steel connecting rods - Probe SRS forged pistons - Dished† pistons available