No problem, but you should know that Gn Reactors are expensive and outdated as a power source.
Also, Leviathan is the name of the PI-9kXE series railgun. Erinamese spacecraft often use these. Even the PI-1 Manta used it since its invention almost a century ago.
The Erinamese Premein, Sortiao and Trelletan fleets jump into subspace, in which relm, the 3ID drive allows the physical properties to be defined. It is a "pocket universe" or a bubble "below" space-time. This creates the familiar "hum" around the universe, more powerful at the location of the bubble. The distortion center is extremely difficult to find, as it is only an exact point, to define it mathematically. The ships cannot forever stay in subspace, as it required 8 A-Class Infinicells to maintain it. It essentially allows craft to simply "pop" out of existence, and appear at any moment. This requires reality and probability anchors, though. These are very small anchors, and cannot be seen by the human eye. If destroyed, all that energy of the matter resurfacing into subspace is given off- a HUGE source of energy that is not even worth trying to contain and should not be used as a power source. However, these anchors are protected remotely by a 3ID System. This system is also able to move or even teleport the anchor.
As for largest ship, the Luna'i is a constantly growing ship, being assembled when not in use. It leaves and joins the Premein fleet as it chooses. It is not nearly as large as the "Leviathan," but still grows at a fast pace. If you want a comparison, I believe that the Leviathan would be about 2.1x the size of the Luna'i when it originally was introduced. The Luna'i is now 1.25x its original size since it has been improved so many times.