Interesting, I rarely see a '76 Carrera RS come up for sale but one was listed on the Early S registry today.
http://www.slide.com/r/4ypAAu6U4D9CKjtJxMseVZbA64jYhwDO
Not the best color IMHO but looks to be in nice condition with a lot of documentation. The case looks to a factory replacement. The seller is asking 'north of $75K', which is not out of line if it checks out with a good PPI.