The first model year engine we found for a Chevy 454 engine was for 1979.
This particular engine comes in two emissions system configurations based on
whether the engine was originally designed for use in California or not. The
California equipped version comes equipped with an EVAP system and an AIR
pump system. The no California version has neither.
I suppose in you specific case you'll need to find out which version of the
engine you've obtained and proceed from their. To our understanding all
emissions components the engine you plan on installing in your Dodge Class C
motorhome was originally equipped with must be installed along with the
engine.