Let's assume for a second that Zodiac was an attorney.
At some point of time, Zodiac focussed on Melvin Belli. First, there is the Dunban TV show. Second, Melvin Belli did recieve a letter on Dec, 20, 1969. Furthermore, he not only did send him this letter, but also referred to him in the Dragon Card ('Please no nasty ones like melvin's). Latter happened in his last sentence in his April 28, 1970, letter. That was four months later. It appears that, after having finished this letter, he felt like adding something more relating to Belli. In a third letter on June 26, 1970, Z again refers to the 'buttons'. I understand this to be again a reference to Melvin Belli's button although he wants them to be with the Z symbol on it. And finally, Tarbox, a SF lawyer claims to know who Z is. So overall, there is some reason that Z might have been a lawyer.
Assuming that Belli's button was one of the American Bar Association (or Californian), it could be a scenario that Z was dismissed out of such a lawyer's association.
If this was the case, Z could still have been a lawyer in SF for a certain period of time. It therefore is possible to find a name of a lawyer that could match e.g. the my-name-is-cipher.
Such a person (I checked approximately 16,000 names of Riverside area high schools - not a single one was a match), would imo somehow be a POI. Again, such a person being connected to SF area and Riverside, would back such a theory.
QT

