Being an "Old Geezer", I and my friends were buying new Mopars back
then. A buddy and I bought a matched set of 1974 Duster 360 4bbl cars.
That being said, the first thing we always did when we got them home
was disconnect or remove any and all polution control devices.

Another little bit of trivia, the 3/4 and 1Ton Dodge trucks were not
required to have EGR or Catalyst until 1979 models.   The steel plate
you are seeing came stock on those trucks to eliminate the lousy EGR
system.

Unless you are going for a "show correct" engine, or need to pass some
communist emission test leave it as is!

Good luck, Bruce