SEPTA will spend $714 million to replace its existing fleet of Reagan-era trolley cars under a deal the authority’s board of directors approved Thursday. Alstom Transportation Inc. will build 130 new streetcars at its Hornell, N.Y., plant, where the company is also constructing high-speed train sets for Amtrak’s Acela service. SEPTA has an option in the contract to buy 30 more trolleys for $148.5 million if it chooses.