While I can not say for 100% sure this is an authentic diner, nor can I say this is a Kullman, it sure looks like a diner. What I do know is that in a May of 1962 classified ad, there was mention of the same Realty company having a Kullman diner for sale. Off hand, I do not know of a Kullman that made it to the Canandaigua region at any time.
Also notice that Mrs. Campbell was from Lancaster. A Robert Estes had a diner in Depew, New York that is still around today known as the 50's Diner, a Silk City. One might believe this is the same Robert Estes. Robert Estes ran that diner from 1955(really sometime in 1954 as the diner is #5425) to 1966 based upon the city directories.