Patrick,
I did exactly that last year. The screen will fit into the same square hole and the top screw holes will align, but not the lower holes. You WILL need to drill/rivet/install new plate nuts for the HDX's two lower mounting screws. That will leave a ~2" gap beneath the screen. You typically can't see that gap because it's under that angled 'button shelf', which blocks your view of the gap...but the gap is there. Dynon sells a filler plate for that gap that screws directly into the old original lower screw holes.
Next, take pictures of EVERY setup/configuration page, then download the config/settings files from your two screens onto an USB stick. You'll be able to upload those files from the USB to your new HDX screens, but having the photos of every setup page allowed me to check how accurately it all loaded.
Once that was all done and I turned on the screens, we were out the gate almost full up. You will need to spend time reformatting/reediting your screen layouts for the simple fact that they are different from the screens on the classic SkyView. Take a look at others' HDX screen layouts and pick a format you like. If you want, I can email you photos of my screens.
You're gonna LOVE the HDX.