R12?
While R-12 is stable, inert, and effective, it is also long-out of production. Try something like R-134a. R-12 is so unbearably expensive, yet R-134a is affordable and I have found it works quite well. I switched my 1987 Volvo over t R-134a from R-12 and am quite pleased with its performence. When I made the switch, it was cheaper to convert the system to R-134a than it was to get R-12, now R-12 is even more expensive.
Nice fridge, I wish I had your luck,
Dave