Update: That Amiga 2000 is the most mint one I've seen, VARTA Battery didn't leak at all, removed it and amazed to see no damage. I may eventually replace the electrolytic capacitors, but it appears to work fine.
I will eventually get back to the Floppie209 replica PCB I spent a lot of time populating the components on it and figure out what is going wrong with that project. But for now I have a fully working system with the Vampire V2 to play with.