To the extent that the Uniform Relocation Assistance and Real Property Acquisition Policies Act of 1970 (Public Law 91-646) makes relocation payments and assistance to displaced persons or other legal entities by states a prerequisite to Federal aid to such states in programs or projects involving the acquisition of real property for public uses, as such terms are defined in such Federal law, State agencies and instrumentalities and political subdivisions and local government agencies and instrumentalities involved in such programs or projects are empowered to expend available public funds for such purposes and are required to make such payments to such displaced persons or other legal entities, whether the program or project is federally aided or not, and such expenditures shall be deemed part of the cost of such program or project.