Camshafts and Cam Timing
The series 2 and 3 motors all share the same camshaft, however the naturally aspirated motors and supercharged motors have different cam timings set in the cam sprocket.
Here is an image of an L67 cam sprocket laid on top of an l36 cam sprocket:
From that image you can see that the L67 sprocket has a cam sensor further counter clockwise than the L36 cam sensor.
This image shows the difference in where the alignment mark is:
From this image you can see that the L67 timing mark is a half a tooth retarded from the L36 timing mark. With the 48 tooth cam sprocket it appears the L67 has about 4 degrees of retard compared to the L36.
Each has different part numbers for the timing set and the cam sprocket. However, the crank sprocket is shared between them.
In theory, switching to the L67 sprocket will cause the peak power to occur ~200 rpm later than with the L36.