REVERE – Two Revere men pleaded guilty to a drug charge after being arrested late last year in what authorities believe was New Hampshire’s largest-ever marijuana bust.Quoc My Tran, 21, with a previous address of 409 Park Ave. and Tai Nguyen, 53, with a previous address of 127 Augusts St., each pleaded guilty on Wednesday to conspiring to possess, with the intent to distribute, more than 100 marijuana plants.In Dec. 2006, police seized about 7,000 plants growing in about a dozen homes in upscale neighborhoods in several New Hampshire towns, including Concord, Canterbury, Hopkinton, Pembroke, Epsom, Hooksett and Weare.Police say the pot was worth about $30 million.State police said the homes had been converted into greenhouses with elaborate lighting and wiring systems to support the plants.Authorities opened their investigation after one of the houses, in Hooksett, caught fire in October 2006 and firefighters discovered 700 marijuana plants.According to a December article in the Union Leader newspaper, Nguyen previously listed his address as 127 Augusts St. in Revere. That’s the same address where a 21-year-old man, also named Tai Nguyen, was shot and killed in a drive-by shooting on March 16.Police said the younger Nguyen died while he was sitting on his couch with his parents watching television.In early October, authorities arrested Anh Vu Nguyen, 20, of Dorchester in connection with the murder. Anh Vu Nguyen is not related to Tai Nguyen. Authorities argued the homicide occurred after a dispute over a woman.