Your numbers are a little off karechar. A spell with both Maximize and Empower on it does not Maximize the Empowered portion and the average of 20d6 is 70, not 60.
Since the Saving Throw for Delayed Blast Fireball would be 4 higher than a Maximized, Empowered Fireball I would rather just use the Delayed Blast Fireball.
Since the Saving Throw for Delayed Blast Fireball would be 4 higher than a Maximized, Empowered Fireball I would rather just use the Delayed Blast Fireball.