The authority having final jurisdiction over any matter in which said Planning Board also has jurisdiction in accordance with the aforementioned laws shall not proceed to such final action until such Planning Board has made its final report thereon to such authority, but if such Planning Board shall not have made its final report thereon within 45 days from the date of reference thereto, the authority having final jurisdiction may proceed to final action. This section shall not be construed to prevent the Board of Trustees from granting, in any specific case, such longer period as it may fix within which said Board may make its final report, and if such longer period is granted, the authority having final jurisdiction shall not, in the absence of such report, proceed to final action until that longer period shall have elapsed.