In addition to the powers conferred upon an authority by other provisions of this chapter, an authority is empowered to borrow money or accept contributions, grants or other financial assistance from the federal or state government for or in aid of any housing project within its area of operation, to take over or lease or manage any housing project or undertaking constructed or owned by the federal or state government, and to these ends comply with such conditions and enter into such mortgages, trust indentures, leases or agreements as may be necessary, convenient or desirable. Any such authority in any contract for annual contributions with the federal government, may obligate itself (which obligation shall be specifically enforceable and shall not constitute a mortgage, notwithstanding any other laws) to convey to the federal government the project to which such contract relates, upon the occurrence of a substantial default with respect to the covenants or conditions to which such authority is subject; such contract may further provide that in case of such conveyance, the federal government may complete, operate, manage, lease, convey or otherwise deal with the project in accordance with the terms of such contracts; provided, that the contract shall require that, as soon as practicable after the federal government is satisfied that all defaults by reason of which it shall have acquired the project have been cured and that the project will thereafter be operated in accordance with the terms of the contract, the federal government shall reconvey to such authority the project as then constituted. It is the purpose and intent of this chapter to authorize every authority to do any and all things necessary or desirable to secure the financial aid or co-operation of the federal or state government in the undertaking, construction, maintenance or operation of any housing project by such authority.