Basically it works like this, the longer your stroke is the more torque you have, the downside to this is that you cannot rev as high as a motor with a shorter stroke or a lighter rotating mass. Torque is essential in drag racing. Horsepower is not a force it is a measurement, Torque however is a force applied to an object. In a car like yours you want as much torque as you can get so the longer stroke you have the more torque you have. And besides building a high reving motor is expensive.
Tyler