Any Multi-Family Residential Building Purchased by a Qualified Nonprofit under the first-right-to-purchase conferred by this Chapter 41B shall be maintained as rent-restricted affordable housing in perpetuity. For purposes of this Section 41B.8, “rent-restricted affordable housing” shall mean that the mean value of all rents paid by residential tenants in the Building shall not exceed 80% of Area Median Income, and that the gross household income of new tenants in the Building shall not exceed 120% of Area Median Income. A Qualified Nonprofit may convert such Multi-Family Residential Building maintained as rent-restricted affordable housing into a limited equity housing cooperative under Subdivision Code Division 11, provided that such Qualified Nonprofit shall fully comply with the requirements of Subdivision Code Division 11 and such Multi-Family Residential Building shall remain restricted as affordable housing consistent with this Section in perpetuity under a new Notice of Special Restriction. The Agency shall establish procedures to ensure that each Building acquired under this Chapter is subject to a Notice of Special Restrictions that: (a) sets forth the manner in which that Building shall be preserved as rent-restricted affordable housing, and (b) provides that no existing residential tenants at the time of the Purchase or new residential tenants following the Purchase may be evicted without just cause consistent with the substantive provisions of Administrative Code Section 37.9(a).