Nice Scamp, sir! It looks like you have the HEI upgrade, that's a good one. Also, a 75 is (I'm all but certain) going to be a lean burn engine. There are a herd of vacuum lines, gizmos, and wiring that go with that business. I trashed all that stuff on my truck since it's not required here, but you may want to investigate that deal. If out of whack it makes the engine run poorly.
You’re probably thinking of the air pump that was put on some engines in 1975. Chrysler’s lean burn system was introduced until 1976 and only then on the 400. In 1977 Chrysler installed it on all V8 engines.