Jeremy,
It sounds like you just want to replace the interior fabric. The interior drapery fabric for your coach was custom sewn in the Beaver factory. So If you want to replace it with identical or similar fabric, you will have to have them custom made.
RV Outfitters in Bend has a good deal of experience with your coach's interior, and they work closely with a former employee of the Beaver factory sewing department who purchased most of the surplus fabric from Beaver when they closed the Bend assembly line, so she may have the matching fabric.
If you decide to just replace the broken cord and replace the fabric later, the average handyman can replace the cord in a hour or so with a little help at times to hold things.
Gerald