The Secretary is authorized to insure mortgage proceeds advanced during construction or rehabilitation or otherwise prior to final endorsement of a project mortgage for the purpose of (1) financing improvements to the property and the purchase of materials and building components delivered to the property, and (2) providing funds to cover the cost of building components where such components have been assembled and specifically identified for incorporation into the property but are located at a site other than the mortgaged property, with such security as the Secretary may require.