Between the publication of TRO2750 and TRO3057 there was shift in the ways Warships were depicted.
2750 showed them like Jumpships, Long but bulkier, see the front of the Battlespace Boxset.
With 3057 depicting them more like naval vessels or Aircraft. In fact the artist for 3057 never saw the 2750 art.
Since the Avatar and Davion were both post TRO3057, IRL, designs, they conform more to the TRO3057 depiction.
I prefer the Avatar model to the Liberator, just ignore the fluff about it being Broken
The Whirlwind and Davion Ships look almost identical in my opinion.
I do believe in Operation Klondike you might be able to find some additional pictures of these ships.
The only other pictures you would have for the Liberator/Avatar, would be in Wars of Reaving maybe. I believe there are some better picks of the Davion in the Handbook House Davion. You might want to check TRO2750 for the older art for the Whirlwind.