Don't get me wrong, I'm not saying "don't include character ships," it's more that I'm suggesting you/we try using character ships that could be representative of a class or somewhat more standardized hull pattern to generate a more broadly accessible hull that could be used outside of a single fleet list for people who don't want to play just one particular fleet list.
To offer a rather lengthy set of examples to illustrate:
We have the Mars-class battlecruiser hull, of which the Imperious was refitted with a salvaged targeting matrix improving its accuracy (optional upgrade). The Divine Right was Lord Ravensburg's command ship throughout the Gothic War, and even gets a 2-page art spread in the BFG rulebook, but despite being retrofitted after extraction from a space hulk, generally fits the template for an Emperor-class battleship despite being probably a relatively unique example of the class. The Vae Victus has been through hell, literally, lost in a warp storm, originally came with prow launch bays (later replaced with torpedo tubes), has been mothballed and reconditioned half a dozen times, had an auxiliary engine room built on after her primary drives were wrecked, and we now use her as the standard example of an entire class of battleship despite her unique history.
For that matter, the original list entries for Battle Barges and Strike Cruisers repeatedly stressed that these were not strict ship templates but meant as catch-alls for a variety of custom-built and "after-market" modifications and repurposings of existing BBs by the Adeptus Astartes over the millennia, generally resulting in up-armored warships with a relatively common set of weapons load-outs tailored to the modern Astartes' specific tactical needs. I guess the suggestion there is that there are probably as many examples of Emperors, Oberons, Desecrators & Glorianas with extra grafted-on armor and rebuilt/reconditioned gun-decks as there are purpose-built codex-standard (i.e., BFG miniature-standard) battle barges floating around out there, and they're all considered battle barges with a relatively abstracted unified weapons set.
I guess what I'm getting at is, the Retribution could simply be a "Famous Ships" entry for the Battle Barge, and we could easily turn stuff like the Ragnarok into an "ancient, mostly-abandoned battle barge variant (grand cruiser hull)" and then use the Ragnarok, belonging to the Space Wolves, as a "Famous Ships" example to illustrate the class. That gets us inclusive templates that more people can use, while giving the Space Wolves their special snowflake (possibly with another sub-class defining "for +__ pts, replace X with Y, or upgrade A to B" option), instead of just getting us a one-off ship entry.
