The Manoora was an expensive rebuild from the basic Newport class, but there is some commonality.
It's a build-up of the original hull, but most of what you need is still there - in this case it's more a taking away than adding (though there's still lots to do there). More extensive helicopter facilities have been added, and the bow has been altered quite a bit, but those are the biggest changes. The drawing at top should provide a very useful reference for converting her back into USS Whatever.
BTW, originally the Aussies wanted to take some retired but still sound ore carriers and make them into clones of RFA Argus. It would've been at worst still cheaper but with better capabilities. Now the RAN has to make do with these dogs and the company holding the ore carriers is struggling to find a buyer. Oh well.