Well, when I imagine a colony ship, I'm think large open spaces to hold supplies, raw material and such. Plus the room for the colonists themselves. Let's go with 5000m, and the dreamer in me would like to see a hangar bay too. Considering the context in which the story line is set, I imagine it would be slightly more heavily armed, and since it would be around 5000m, how about a few AAAf's, some Flak cannons, and one LTerSlash in each direction(front, back, left, right).
I was planning on using the beat up Orion for as one the last NTF ships, but I can still use a regular looking Orion. The beat up one would only look REALLY cool.
Thanks for the help, seeing your name on this forum was a God send.