5.7L/ABS Donor Car for 1967+ Dart

got a quote for a cam from Schneider, IIRC it was .580 lift, 216 split duration. Nice cam for a 'sleeper' and/or 'turbo' car.
can't find inconel exhaust valves for the 5.7L, are they made? if not, what's the next best thing for a turbo exhaust?