In order to facilitate visitor travel, provide scenic overlooks for public enjoyment and interpretation of the national lakeshore and related features, and in order to enhance recreational opportunities, the Secretary is authorized to construct and administer as a part of the national lakeshore scenic roads of parkway standards generally lying within Benzie County and within the parkway zone designated on the map specified in section
of this title. Such scenic roads shall include necessary connections, bridges, and other structural utilities. Notwithstanding any other provision of this subchapter, the Secretary may procure for this purpose land, or interest therein, by donation, purchase with appropriated or donated funds, or otherwise: Provided, That land and interest so procured shall not exceed one hundred and fifty acres per mile of scenic road, except that tracts may be procured in their entirety in order to avoid severances. Property so acquired in excess of the acreage limitation provided in this section may be exchanged by the Secretary for any land of approximately equal value authorized for acquisition by this subchapter.