The deal with Chrysler's color coordinating interiors, is that they are not the same paint code as the outside of the car. They may look close, but the interior colors were finished in what is referred to as a suede finish and the color, itself, is actually a different formula.
Organisol is very similar, but it is a little too coarse in texture. This paint was formulated, using the same texturizer, but has less of it to get the correct finish.
What you may have to do, if you are going totally legit, is to get the Ditzler interior paint code page from 1968 and find the color, that way.
If you can get the Ditzler code, PPG has cross references for the toner, but it may not be the correct texture/ gloss.
If I were you, I'd get ahold of some suede paint. There is a guy who formulated some and sells it, or you can get ahold of some PPG organisol and cut it down as you please, to match texture, then shoot the basecoat color over the top and leave it.
GG1 is a '68 only code. in '69, the color may have been close, but the fender tag went to a single alphanumerical deal (F8, for example, instead of two letters with a number following).
That suede paint is actually what they used on factory Gull and Go wings, as well. I've used organisol and the suede paint, I have both and they are close, but the suede is without a doubt, exactly what they used on the dashes of these cars, black or in color.
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