A corny keg is 25″ high and 8.5″ wide (I just measure one in the basement).
I drew up a quick cylinder of the same side and placed in inside the keg box of the EHBP-03 plan.
As you can see, it fits with plenty of head room to spare. albeit 2″.
(note, the darker pink layer of foam above the keg is the top sheet of foam seen on edge, so it’s a little deceiving)
[attachment=0:97ap2jhr]corny keg comparison.jpg[/attachment:97ap2jhr]
As designed, the interior dimensions are ~ 32″ long x 27″ high x 19″ wide.