The new 340,000 facility marks Pennsylvania’s largest manufacturing investment since Hershey built its former West Hershey plant in 1991. The Hershey Co. has opened a $300 million, state-of-the-art plant in West Hershey, Pa. to produce Hershey’s Bars and other chocolate products, including up to 70 million Hershey’s Kisses a day, the Philadelphia Business Journal reported.…