Let the normal at the point $P$ on the parabola $y ^ { 2 } = 6 x$ pass through the point $( 5 , - 8 )$. If the tangent at $P$ to the parabola intersects its directrix at the point $Q$, then the ordinate of the point $Q$ is\\
(1) $\frac { - 9 } { 4 }$\\
(2) $\frac { 9 } { 4 }$\\
(3) $\frac { - 5 } { 2 }$\\
(4) $- 3$