Serpentine or non-serpentine has nothing to do with Fed or CA certs or A/C- Non A/C. It was just the progression from the old, V Belt set up to the modern Serpentine, though it was not pulled off very well with the 258's.
Serpentine belts have much larger contact area with their driven components and are less prone to heat/stretch issues. Additionally, they are suPPOSed to be easier to change (and on most vehicles are!) since one broad belt is used to drive all components (at least that's the way it is on MOST vehicles) with one adjustment point or tensioner. Unfortunately on the 258 it really wasn't planned as well as it could have been and is a marginal system a bit more difficult to deal with than it should be, though it is not untenable.
One thing with the Serp system is it is much more difficult to "lose the emissions" components to those who are so inclined. Many have made the mistake of reverting to the old Vbelt system, without planning to change the water pump with it!
I believe the change to V Belts occurred after the Chrysler Purchase in 86, however, I had an 88 with V Belts and I have had an 86 with Serpentine.
Have a great week!