In connection with any housing project located within the area in which it is authorized to act, any state public body may contract with a housing authority or the federal government with respect to the sum or sums, if any, which the housing authority or the federal government may agree to pay, during any year or period of years, to the state public body for the improvements, services and facilities to be furnished by it for the benefit of such housing project or the persons residing on or occupying such premises, but in no event shall the amount of such payments exceed the estimated cost to the state public body of the improvements, services or facilities to be so supplied; provided the absence of a contract for such payments shall not relieve any state public body from the duty to furnish, for the benefit of such housing project and the persons residing on or occupying such premises, customary improvements and such services and facilities as such state public bodies furnish customarily without a service fee.