That we know of. Apparently he's linked to some other potential crimes, mostly circumstantial evidence like "he was in the town the same day" or "that girl went to his store once." But just because he got found out for his crimes connected to people he was close to doesn't mean those are the only ones. As far as I can tell so far, Morris Black was a stranger. I don't see how he had any connection to Robert Durst apart from being a neighbor while he was living below his means while dressing as a woman.
Here are some interesting details about Zodiac and Durst:
*Zodiac used a 9mm and a .22 caliber in his shooting murders. Susan Berman was shot with a 9mm and Morris Black allegedly struggled with Durst over a .22 caliber gun.
*Zodiac was alleged to be in his late 20s or older, but the Lake Berryessa witness who conversed with him the longest wondered if he was closer to his 20s than 30s. Durst was born in 1943, which made him 26 in 1969.
*Zodiac was described as having a drawl but not a Souther drawl. One of the female victims was able to describe his voice as "precise" but neither high nor low, just clear. Durst has a very unique speaking voice, emphatic in how he says certain words, and one that could be described as having a drawl. His customary gravelly sound may have developed with age due to smoking habits.
*Zodiac killed men and women. Durst killed both, too.
*Zodiac spelled words wrong in block-writing communications with police. Durst mailed an all-caps letter to "Beverley Hills Police" that specified where police could find the body of Berman.
*Zodiac referred to changing his appearance in his communications with police. Durst is known to have dressed as an elderly woman to avoid identification in Texas and shaved his eyebrows and head to project a different image when he went on the run. His appearance in early years with his wife also rapidly changed, from bearded and clean-cut to no facial hair and wavy long-ish hair to the weird Prince Valiant haircut he had in his 1973 wedding photo.
*Zodiac was active from 1968-1969 in terms of their crimes. From 1970 onward, he does not kill anyone else that police can tie to him and only letters sporadically arrive. By 1974 it is suspected that he has moved or gone to jail or died. Also important, it is presumed something in the Zodiac's life changed momentously and caused them to pursue their crimes when they did. From 1967 to spring of 1969, Durst was at UCLA studying economics in a graduate program. At some point in the late fall of 1968 or early 1969, he was "called home" by his father to work for the family organization. It's unclear when exactly this employment began or how in earnest given that in his own words he did not go into the office much.
*I would also add there is considerable additional evidence that Durst had ties to the San Francisco area and actually commuted to SF from NY before traveling to LA by car to kill Berman. He commuted back to SF to fly out to NYC. So that already suggests the distance between the California cities was nothing to him as a driver. Moreover, his wealth would make it very easy for him to have traveled between NY and SF without arousing suspicion.