[JoeC]

The 1968 Z-28 Convertible probably is one of the highest valued Camaros on the planet but was not a production car. It was a one off custom built by Chevy. There were a number of these one off cars built but most did not escape the factory unharmed. Some may have escaped with changes then sold to GM employees. The design head Bill M. did a 1970 ZL1 Camaro which he was allowed to purchase and bring home. He then rebuilt/restyled the car in 1977 but I think it still exists. There were two 1969 ZL1 prototypes built but have not been found. I think there were 5 or 6 Pace cars that were prepared for use in the Indy 500 race and were custom built. Over the years, there were many of these one off's built by Chevy.
As far as rare Camaros that were built through mostly normal assembly process, the L89 convertible had to be low in production quantity. How about a L89 Pace car or L89 Z10? The cars with dash (-) on trim tag have to be low numbers also. So a L89 RS SS convertible with special paint would be among the most rare production Camaros if there even was one built. Unless some new info is found showing original options, one can only guess.