Section 6. Upon the approval of this Act, any other branch or agency of the Government administering properties transferred to the Republic of the Philippines under the Philippine Property Act of 1946 and of Republic Act Numbered Eight shall immediately turn over to the National Abaca and Other Fibers Corporation all records, titles, plans and surveys affecting the lands described in the title and in Section One of this, including the proceeds and/or income thereof: Provided, however, That the National Abaca and Other Fibers Corporation shall retain for model plantations and/or experimental stations and seedling purposes a total of not exceeding two thousand five hundred hectares.