Actually, it's 2AM here, I've forgotten the name of the thread myself...
I ended up with a family of weapons, to go no further than that, which were derived essentially from the other weapons we see in the game, Rutarian ion bolts, ion torpedoes, etc.
Ship- mounted Ion bolt Cannon were range 8 Double Precise, Heavy Ion Bolt Cannon (replaced the Darkner's battle lasers) were 16, AP Double Precise. They were related to the Ion Lances- 18, Super AP Precise, and Heavy Ion Lances- 20, Super AP Triple Precise.
Possibly Lances and Bolt cannon should be heavier and Slow- Loading, trading a bit of extra oomph- Bolt Cannon at short and Lances at long range- for fire delays.
Standard Ion Cannon had ranges from 12 to 18, and generally AP.
Medium Ion Cannon were generally range 24, at least AP and usually Precise,
Heavy Ion Cannon range 24-30, AP Double Precise, sometimes Super AP.
Superheavy Ion Cannon (Octurion, Adira) hit the end cap, really- 36, Super AP Triple Precise.
I was not overly generous to plasma streams, not doing much to their ACtA stats at all, but I did assume that the Vorchan's plasma accelerators should be SAP- there was a tactical aspect to it, the big ion cannon dismember an enemy ship and the plasma and matter cannon equipped ships roll in to finish it with bulk damage.
There were a few Ion Repeaters about the place, which were essentially late development, post EMW weapons, in the light of what the Centaurum saw of Minbari capabilities. They threw ion packets, compressed sequences of pulses, becoming effectively Mini-Beam. This might be a technical step too far.
As far as actual beams went, I was presuming that apart from the plasma stream, most of what beam weapons the Centauri should have are either League- derived (I have wanted to steal the mag gun, which is based on Centauri technology after all, back for some time now) or Shadow and Drakh derived, with range and traits- no 35" molecular slicer beams thank you- close to the original installations.