I have not seen another Zunow with those Campy dropouts. I have seen several early-'80s examples with Suntour dropouts and the chain hanger mounted a ways up on the seatstay. One of those is for sure an '81. So if (BIG if) Zunow was consistent in a given time period in their use of frame parts, I'd say yours is not later than '81.
BTW, I would love some pictures (or the frame itself :)).
Dave Ross Portola Valley, CA
PS aforementioned early-80s Zunows may be seen at
http://www.wooljersey.com/
harvey sachs wrote:
"Some time ago, I became the caretaker for an all-black but somewhat be-draggled Zunow frameset. Actually pretty conventional for a Zunow, but does have the Pentagla chainstays, and hummingbirds engraved on crown caps and seat stay eyes. And h'bird shaped BB "drain" of rather large size. 57 cm seat, ctc; 55 cm top, ctc.
It can't be earlier than 1977, since it actually has short Nuovo Record
dropouts without eyelets (drilled and tapped for chain holder), which
the Campy Time line http://www.velo-retro.com/
A question: when was this special chainholder rear drop discontinued? That would roughly bracket the age of the frame."