Simplest solution for keeping the GG installed while using a Grafmatic on the Meridian would be to add stacked washers or a couple of drilled spacer blocks about 1/4" thick under the leaf springs. You might need longer screws, but these are common enough threads (if I recall correctly 6-32?).
Using a Grafmatic or Quickloads in portrait mode, I greatly prefer either of my Meridians to the Super Graphic with a top-mount RF I once owned, since with the Meridians I can leave the darkslide oriented up and still see through the RF. Too, the wire hoop action finder is better executed on the Meridians, with a closer approximate view in portrait mode. (With the Meridian style hoop that flips up, one can even install and leave wire frame sliders to it, set for the framing requirements of a roll film back.)