As has been said, AoG made Fleet Action and Babylon 5 Wars scales. Mongoose capital ships are almost all the same size as Babylon 5 Wars. One exception is the EA Olympus; the original Mongoose model was the same as the Babylon 5 Wars one, then they produced a smaller one similar in size to the Fleet Action one and sold them in packs of two. This smaller version is closer in scale to other EA ships such as the Hyperion.
Mongoose's fighters, on the other hand, were almost all the same as AoG's Fleet Action ones, six small models on a hexagonal base. There were some exceptions; some heavy fighters such as the Drazi Sky Serpent were the Babylon 5 Wars ones, a single larger model on a base. And Mongoose's White Star Fighter was basically AoG's Fleet Action White Star ship.
(Didn't Mongoose take over the AoG moulds?)
Back to the original question about painting Narn:
I did my
G'Quan by painting the main surfaces overall white, outlining the red and black areas with marker pens, then filling them in with paint. Once I was happy with the pattern, I did the grey rim and metallic central bits. There's also a green bar across the middle of the main hull with a logo on each side. The logos are decals I printed out myself.
The guide to ships of various races is here:
Ships of the... (Index)