If it's just for measurement, a U-shape cut out of sheet brass or aluminum with shears will be fine (the U is the slot so it can pass under the stand without removing the bolt).
AFAIK, the deck and the upper surface were made exactly parallel, which means that inverting it to level on a mill bed (unless the guides are out, you'll need blocks to span these areas) and passing a quill and dial indicator across the length will give the error in thousandths.
Last edited by panic; 01/25/10 02:15 PM. Reason: Ooppss
