Well, I was wrong about the interior measurements of the diner, in this photo you can see our Zombies on 30mm bases where they will fit.
In this photo are two figures the Am. sailor ACW is on a 1 inch base and will fit pretty much anywhere behind the counter. The Trent Highlander is on a 2 pence piece and will only fit between the stool and some behind the counter. Without the stools the measurements work fine and 30mm bases will go anywhere in front of the counter.