Until procedures for determining operating cost payment rates according to mix of resident needs are established for nursing homes that exclusively provide residential services for nongeriatric individuals with physical disabilities or units within nursing homes which exclusively provide geropsychiatric services, such nursing homes or units within nursing homes may not be included in the calculation of the limits of any cost categories. Each of these nursing homes or units within nursing homes shall receive its actual allowed historical operating cost per diem adjusted by the inflation rate for nursing home services used to develop the legislative appropriation for the department, and which the department determines to be relevant to residential services for nongeriatric individuals with physical disabilities or geropsychiatric services.