I used original air as well and thought fit was good but the ac mounting bracket was not painted( as mentioned) so do that first. With the sanden compressor I did not need to add a idle speed motor to carb. The sanden compressor does not drag down motor like stock compressors. I have a different opinion on OE compressors, they leak and fail at a higher rate then sanden compressors. I used my original evaporator just flushed it and everything is working fine. My biggest complaint is the OE fan motor does not create enough flow compared to modern vehicles. On hot days fan motor is in high the entire time
I started out with an original rebuilt A6 compressor from Napa and went through 2 in 2 years. Here is the kit I used
https://www.originalair.com/77-81-fi...ile-v8-stage-1