I don't want to burst your bubble, but most all the black plates were used up with the 1968 model year cars. All the 69's seem to have the Blue and Gold plates.
Both California black plates and blue plates were issued to new cars in 1969. The previously-owned '69 340 Swinger I purchased in November 1969 had black plates. The plates were toward the end of the black plate era because the first letter on the plate was a 'Y'.