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.

From those pictures it is easy to see that the L67's cam alignment mark is slightly further clockwise than the L36 cam sprocket. The timing mark appears to be a full tooth further advanced on the L67 sprocket. With 48 teeth this would indicate that the cam is actually 7.5 degrees advanced on the L67.

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 horsepower to occur ~800 rpm sooner than with the L36.