I'm betting it's still portable.  My dad did the same thing when he rebuilt some of the kitchen cabinetry.  At that time we had the uber BOL Wardgidaire portable top loader from around 1970.  Ever since, actual built-in dishwashers have had to be put on skids to eliminate a gap under the counter top, until the installation of a Miele tall tub this past August which filled the space without the need for skids.