Original 340 Exhaust Systems Help

I am looking for a vendor for an original 340 exhaust system using the cast iron manifolds for a 1970 Dart Swinger. Did these cars use an "H" pipe? I also see "X" pipes? 2.5 pipes? 2-1/4? I would want at least and aluminized system if not stainless. Any advice for mufflers? I intend to use the exhaust tips as well. Thanks