Factory AC Dart and options

Step 1-

There is one wire to the compressor.

Apply 12v to that wire. Turn the AC on (might be easier to turn AC on first) Does the AC clutch engage?

If the car is running, and the clutch is engaged, does air come out of the vents?
Is it cold? Cool?
Does the fan speed switch work?

Do NOT add refrigerant with "stop leak" at this point.

The next step is going somewhere with gauges and a recovery tank.

Stop leak will contaminate a recovery tank.
Most shops won't evacuate your system if you've put stop leak in.

If the system checks out, I'd go for a 123a conversion.

It;s likely you'll need seals and a new dryer.
You'll also need conversion fittings.

If the compressor is shot a sanden might be the way to go, but it takes different mounts.