I finally found a copy of this rare accordion-fold brochure which shows the incredible number of paint and upholstery options available for both the 1500 Ghia coupe and cabriolet in 1963. This copy is undated, but I've seen other copies that carry the date "1/63," when Karmann was still gearing up for the cabriolet production run that unfortunately never happened. On the bright side, the decision to halt production of the cabriolet kept a manila yellow Ghia with a black and yellow interior and a red convertible top from ever being produced, so we can be thankful for that.
This is an odd brochure because it doesn't correspond to the options that were actually available to the public in 1963. In addition to the cabriolet never being available for purchase, there were other interior color options available in 1963 that don't appear here, such as the option of red interiors for anthracite cars and the black vinyl interior option for all car colors, as documented in The Samba's Type 34 color reference page. Maybe these additional options were introduced sometime later in the 1963 model year in reaction to public demand or criticism in the press. Road & Track's February 1963 road test of a 1962 model described the available interior color combinations as "garish and tasteless." That must have hurt.