Unpopulated playfield:

centre of the top slingshot screw graphic - 294 mm
Centre of the bottom slingshot screw graphic - 221 mm
measurement of the width of the playfield - 514.5 mm (presumably 20 1/4 inch, which is 514.35 mm)
measurement of the length of the playfield - 1168.50 (presumably 46 inch, which is 1168.40 mm)
measurement from the bottom of the playfield to the very first screen print graphic. - 55 mm but a bit hard to be precise as the tip of the graphic is a little worn. Maybe some other reference points to match up would be useful.

Have fun!