I use a combination of the suggestions from Battlefleet Gothic along with some pointers Andy Chambers sent me many, many moons ago.
Fun 40K trivia fact: truly ancient ships with Latin names (as well as truly ancient Titans) actually have Latin names, not "this is pseudo-latin that is actually a fill in for the baroque far future word that you wouldn't understand" but "this is actual Latin from Old Terra".
"Truly Ancient" generally means "Dark Age of Technology".