There are authorized to be appropriated such sums as may be necessary to carry out the provisions of sections 228a to 228j of this title, not to exceed, however, $1,250,000, in the aggregate for the period of the five fiscal years beginning with the fiscal year ending June 30, 1974, for the acquisition of lands and property, and not to exceed $49,000 for the fiscal year ending June 30, 1974, $255,000 for the fiscal year ending June 30, 1975, $265,000 for the fiscal year ending June 30, 1976, and $235,000 for the fiscal year ending June 30, 1977, for development, plus or minus such amounts, if any, as may be justified by reason of ordinary fluctuations in construction costs as indicated by engineering cost indexes applicable to the types of construction involved herein. The sums authorized in this section shall be available for acquisition and development undertaken subsequent to January 3, 1975.