A New Jersey restaurant boasting the longest uninterrupted run of business in the state is closing for some time. The Black Horse Tavern & Pub is set to close on March 4 for major renovations. The almost-300-year-old eatery, located at 1 W. Main St. in Mendham, will undergo remodeling of its kitchen, dining room, bar and outside space. Mendham’s Black Horse Tavern & Pub is expected to reopen this fall although an exact date has yet to be determined. The tavern has been in business since 1742. Its menu features burgers, sandwiches, pasta, steak, seafood, pot pies, soups, salads and more. Morris…