Just take the drivers side box and put it on the passenger side. It will bolt on. But the door will open the wrong way. And will rub a little against the kick panel.
Since the right side (body)flange doesn't have threaded studs like the left you can turn it 90 degrees(or whatever degree you desire) and the door will open without hitting anything, you will of course have to use a bolt/nut application.
That's my plan anyway
I was also going to inquire in this section about a right side heater delete fresh air box but figured I would be waiting a long time for a reply.