Notwithstanding the provisions of this chapter or other law, a single body may serve as both the assembly and school board in the manner provided for third class boroughs under AS 29.20.300(b), if
(1) an ordinance for that purpose is approved by the assembly and ratified by a referendum of a majority of the qualified borough voters voting on the question at a regular or special election; and
(2) the public school population within the borough is 500 pupils or less.