Unfortunately a two toned paint job was often done to a buyer or dealer preference so it will be very hard to find out, there are multiple resto books out there but not too sure who would have those numbers

You might be interested in the book [u]Chevelle SS 1964-1972, A Muscle Car Source Book, Second Edition[/u] Don't know what information they have but definitely worth it if you own a Chevelle SS. You can probably buy it from Amazon or Barnes and Noble or your local library might have a copy.