I just purchased a new A/C systems for my factory air 72 SSP. Instead of converting the old system I decided to convert over to a newer style system. I purchased my system through BPE.
http://www.bpeusa.com/
I spoke with both Vintage and Classic but they didn't offer kit for my 72 B-body. I would have had to purchase a universal kit and adapt it as needed. So far the kit from BPE has bolted right on without issues. BPE offers kits for both factory A/C and non-A/C cars.
Below is photo of the compressor installation that I just completed about a week ago.