Remember, too, that 134a is very cheap. Proceed with little fear of experimentation, "trying your luck" with the old compressor, and keeping your current hoses.

If something goes, it's just a mechanical swap out, suction and refill.

A local independent Volvo shop stayed away from the expensive "replace everything"
scare when the conversion craze got going a fewe years ago. This is when you were being told the R12 hoses couldn't handle the higher pressure, or were not barrier hoses needed for 134a.

They merely purgedd the R12 and oil, evacuated, and filled with 134a and its oil.
--
'Can't understand why people abort Volvos, either' '89 740 Turbo, 122,000 miles