Wente Bros. Winery has sold 600 acres of vineyard land to a joint venture comprising Signature Properties of Pleasanton and a golf-course development company led by Jack Nicklaus. The property, between Pleasanton and Livermore, Calif., is on the old Ruby Hills Vineyards, purchased by Wente Bros. from ComputerLand in January, 1986. Philip Wente, vice president of the Livemore-based family winery, said Wente Bros. will retain 200 acres and the historic Ruby Hills winery building, built in 1887. Wente Bros. received $3.5 million in the deal and could realize an additional $2.5 million if the buyers can gain development approval by the end of 1990. Wente said the proposed custom-home and golf-course development is what Wente always envisioned for the land. A referendum in Livermore last month overturned city approval of a new housing complex that was feared could harm nearby vineyards.