rough sketch of how the panels go together.





Actually, just thinking about you van and the sunroof you may be better off replacing the entire roof and side panels as one. Cut your Sandman along the yellow lines and the HZ along the pink lines and fit the entire HZ roof and side panels to your Sandman... You will need to transplant the hoodlining strips to the HZ roof section. Probably be easier and more accurate doing it this way and you will get a better finish rather than trying to weld an infill into the roof to fill the hole.

Pretty much like what T Dog did to his in the pics on Fastlane.