When I had to reduce the height, I just scribed a line the correct distance from the top and ran the track saw the whole way round and then rounded off the top corners if the cut out again.
Unfortunately not, and fuck knows where it is. But the base is recessed about an inch (you can se from the line of screws along the front, not exactly award winning joinery) and I used these castors.
When I had to reduce the height, I just scribed a line the correct distance from the top and ran the track saw the whole way round and then rounded off the top corners if the cut out again.