Tyrants can also take Nova Cannons by the way.
Do you think you need the extra range of the tyrant as you already have three ships with battleship weapons range range, the Retribution, Emperor and Overlord.
The Tyrant, souped up of course, is basically a weaker battlecruiser with cruiser turrets. A Dominator can do basically the same job within a fleet for 15-25 points which could be another Cobra if a few points are saved elsewhere or a admiral reroll.
Two tandem Dominators can be very lethal both with twin Nova cannons long range and 24 weapon batteries in close.

I use Tyrants as scout fleet flagships supported by escorts and light cruisers or as a support cruiser paired with a battlecruiser.