The proposed construction of a new middle and high school building recently cleared a key hurdle when the Massachusetts School Building Authority agreed to provide partial reimbursement for the project. The School Building Authority committed to providing 59.97 percent of the eligible costs of the project, or up to $42.5 million. The action sets the stage for voters to consider a debt exclusion, or temporary tax increase, to cover the town’s share of the total $80.2 million project. That vote will be on the ballot for the Nov. 5 town election. The proposed 187,917-square-foot school would serve up to 970 sixth- through 12th-grade students. The current school was built in 1965 and needs a multitude of repairs, including to its stairs, exterior, windows, and roof, according to officials. It also does not meet requirements to provide access to people with disabilities. The new school would be built on the site of the existing high school building, which would be demolished.