The shorter stroke allows the higher RPM which was stated above. The reason is that with a shorter stroke, the pistons move much slower at a given RPM than an engine with a longer stroke at the same RPM. Look at it this way, in a small block 400 with a 3.75" stroke at 1000 RPM, the piston moves 7.5" for every revolution. Thats 7500" in one minute. A 327 with a 3.25 stroke has pistons that move 6.5 " every revolution. Thats 6500" in a minute at 1000 RPM. In order for the 400 piston to move the greater distance in the same amount of time, it has to move faster. The faster piston velocity makes it much harder for the piston to change direction at either end of the stroke. Therefore, shorter stroke equals slower piston velocities and higher RPM capability as long as the valve train will hold up.