The 740 slips right into the AirGizmo Panel Dock for the 720/700. It fits the 740 too. You can get the panel dock at Aircraft Spruce for about $115.
I have mine mounted vertically in the 172 recessed into the AirGizmo Dock in the center stack. I'll see if I can find a recent pic. Nice and clean install. My 68' 172 is a VFR bird with not much else in the center stack. Call me old school, but I like the less is more approach for my type of flying.