there are really 3 choices, all 3 are going to require some work on your part to fabricate some items.
vintage air
classic auto air
bouchilon(sp)
all 3 make under hood portions, only the first 2 make under dash pieces.
a 383 should be pretty easy to get the new sanden compressor to mount with any of the 3 makers.
I used classic auto air. felt they were a little more mopar friendly.
however, no one is going to offer a direct fit for a c-body under dash.
what I did was make a mounting plate for the under dash box, and had that plate bolt up to where the old heater core was.
if your newport had a/c and you are just trying to make it work, classic can rebuild the a/c box under the dash, and you can pick anyone for the under hood parts.