Manley has a valve that is USA made and they KNOW which alloy to send you for that application--none better Todd at Moparts Connection a sponsor here is best Manley dealer in the country--they will work! As in boats, boosted engines are Murder on exh valves and most turbo/boat engines fail because of exh valve failure--Those Eddy valves will drip off like a marshmellow over a camp fire when exposed to load/boost
Trust Manley tech advice/get part number-- and then order from Todd--they will be on your door step in a couple of days--use them until you retire then sell them