I have an '85 25', which is fundamentally the same coach.
The basic layout is no different than the current production model Classic. The current coach is wider, of course. but you can see the floorplan on the Airstream site.
Colaws RV Salvage in Carthage Mo has a good couch from the proper period - but I doubt they know it. It is sitting in the front of a salvage unit, with the wind and weather blowing in through the broken window. However, any couch of the proper period is going to need new fabric and cushions. They ship, but don't let them kid you - it is worth very little. Note that there are little compartments on either side with curved cushions on top to fill out the space to the wall. And the whole thing sits on a frame of 2X4s. Unless you can come after it, they will charge mostly for having to crate it up and shipping it.
Ours was miserable when we got it, but with new upholstery and cushions it is a very pleasant place to relax, read, or watch TV. And we like the folding table, but there are just the two of us.
You might want to take a look at my photos (click on "photos" below) to see how I built a new credenza/folding table, and our "new" couch.