A mortgage financing the purchase or refinance of an existing rental housing project or refinance of the existing debt of an existing cooperative project under section 207 of the Act, or for refinancing the existing debt of an existing nursing home, intermediate care facility, assisted living facility, or board and care home, or any combination thereof, under section 232 of the Act, may be insured pursuant to provisions of section 223(f) of the Act and such terms and conditions established by HUD.