You might find a new compressor that uses the same refrigerant, and you might not. Plus, efficiencies of newer designs means you may not get the best possible from the unit. So, it really depends. You'd need the specifics of what's installed now to then compare with what's available. Regardless of how well you pull down the existing unit, the oil and refrigerant that's there now will still have contaminated it, so you must remain compatible when installing a new unit.