Yeah, that's a quick and dirty way to get it working...
Changing over to a Sanden compressor and updating all the mounting brackets, pulleys, lines, etc and get overwhelming and expensive and get complicated...
The R-134 A in the R-12 system with just the basic updates should work ok, just approx 3° - 4° warmer.... No biggie, it will still keep you cool from that heat in the south...