Took a reccie to the Fine Timber Company (fm. the Timber Bloke), and couldn't leave this bookmatched she-oak pair behind. They're about 12mm thick, 200mm wide at narrowest point, and 500mm long. So plenty to work with.
https://i.imgur.com/6oZRV67.jpg
Now thinking about what the bottom to this top will be, but will likely be limited in single piece options if I want to compensate for the bookmatched top.