Simplify the expression (y - xy^5) / (3y - x) * 2(x - 3y) / (x^4 - y^4) for x = -1/7 and y = -14.

1. Simplify the expression: $$\frac{y(1-xy^4)}{3y-x} \cdot \frac{2(x-3y)}{(x^2-y^2)(x^2+y^2)} = \frac{y(1-xy^4)}{3y-x} \cdot \frac{2(x-3y)}{(x-y)(x+y)(x^2+y^2)}$$.
2. Substitute x = -1/7 and y = -14 into the simplified expression.
3. Calculate the final value.