I converted a Craftsman arm saw into a panel cutter and in the process found that, as pminmo stated above, the side loading tolerances just are not there...also the arm is heavy and would require a substantial motor to lift it. For the time and trouble involved in overcoming these limitations I would place my energies at a different starting point.
Neat idea though; it is on the right track....after a while anything that slides will look like it has potential. Gee! Wonder if I could turn an Arby's meat slicer into a CNC machine....