That old system was good. I would repair it. Those compressors are rugged & available cheap used all over the place. Replace the comp., flush the system, put in Easter oil & you will be good to go. The vintage-Air is a good system. I put one in my 70 when I had it because it didn't have factory air. It was a lot of work. It still was not as good as factory air.
The one big advantage is freeing up space under the hood.