The Board of Selectmen on Tuesday authorized seeking architectural and engineering firms to study the former Bantam School and determine how much it would cost to overhaul the 70-year-old building for continued municipal use. Proposals would show how much an architectural and engineering study of the building that was designed by famed modernist architect Marcel Breuer would cost. Preliminary estimates have ranged from $100,000 to $500,000. The committee, in its final report to the selectmen in the spring, recommended an extensive renovation of the former school after two years of discussion and study. According to the review committee, a $10 million renovation would be feasible because in 2024-25 the town will pay off $24 million borrowed for a school expansion and renovation project completed in 2009. A tax increase would not be required for the renovation, according to the committee.