I'm with Rick on this one. R12 is still available and as I understand
it, the price has come down from what it was a few years ago. I would
fix any leaks and have it recharged with R12.

I converted my MB 10 years ago when I needed a new compressor and R12
was through the roof and it looked like it was going totally extinct.
While the AC is adequate, I'd say it probably has about 20% less
cooling capacity now.