Roadtrip may chime in with the gospel on the differences, but yes, a single throat throttle, cast airbox needed due to the heat of EGR (for the first time) air filter over on the exhaust side of the engine, different manifold, different Spica pump 3D camoid, different (three tang instead of two) lockring on the fuel cutoff solenoid. Also different setup for idle air, requiring a couple special tools.
If I had a good running one with good smog numbers, I wouldn't mess with it, I'd run it til it didn't pass smog any longer. Current cats are better than period cats, so if everything's working it might pass fine.
Andrew