Here are two alternatives available to you: Option 1.
The good news is that there are gasses which are a direct replacement for R12.
The gas we use is commonly known as R437 or R437a (Isceon® MO49Plus™).
This is the most up to date replacement for R12 (and supercedes RS24 / R426a).
Shortly thereafter, fellow hot rodders hired Chisenhall to install A/C on their muscle cars as well, and soon Vintage Air opened its doors to the public in 1976.