Converting from mechanical to hydraulic cam and lifters on 273 Dart

Which hydraulic system are you referring to?

A set of stock hydraulic rocker arms, shafts, and pushrods. They can be found on any 68 up 273, 318, 340, or 360 till he magnum engines. Just clean them up, inspect then, oil them up and bolt them on, Done. Just make sure the shafts are oriented correctly. The rocker system changed again with the magnum engines in the 90's to pedestal rockers.