Based on his wording in the cracked 408 cipher: "I will not give you my name because you will try to slow down or stop my collecting of slaves for my afterlife", it may be possible he signed off the 340 cipher with a phrase something like "I will not tell you who the Zodiac is", bearing in mind the positioning and appearance of the symbols on the last line.
We know that he placed what appeared to be three circled 8's on the 13 Symbol cipher, but why did he circle them? Was it to highlight the fact they had increased significance? In a previous article we highlighted the symmetry contained within the 13 Symbol cipher. https://www.zodiacciphers.com/zodiac-news/the-symmetry-of-the-13-symbol-cipher
So can we generate the same symmetry from the only apparent reference to the name ZODIAC on the final line of the 340 cipher, to provide us with that seamless link.
We will use the identical technique featured above, by alphabetically counting the numerical difference between the letters in the cipher and the key chosen. In this case, the key is the killer's pseudonym ZODIAC, because it is without doubt the most significant marker he placed on the 340 cipher - and it is difficult to believe he placed the 'near Zodiac'on the final line by sheer accident during the construction of the cipher.
888 is a unique number, explained here in Wikipedia. In Christian numerology, the number 888 represents Jesus, or sometimes more specifically Christ the Redeemer. This representation may be justified either through gematria, by counting the letter values of the Greek transliteration of Jesus' name, or as an opposing value to 666, the number of the beast. In Chinese numerology, 888 has a different meaning, triple fortune, a strengthening of the meaning of the digit 8. For this reason, addresses and phone numbers containing the digit sequence 888 are considered particularly lucky, and may command a premium because of it.