I took one of the seats apart and was surprised to find out that they had been recovered.  All along I thought they were the original leather, but after looking at some pictures, it was obvious that the piping wasn't original.  Then, when I got the back cover removed I found that they had simply pulled it over the the old seat, leather and all!  So now I have to decide if I'm going to put out the cash for new leather.  It's available from Moss for about $430, so it is't too bad, but the cost of this project has gone way beyond what I had anticipated.  Oh well, it's only money, and you can't take it with you.
 

Here are several pictures of the seat as I took it apart.

 

Here's the old seat back that was found inside the cover.