I plan on doing this job myself and hope not to do it again
When you do, will you replace the Condenser, Orifice tube, and receiver/Dryer as well as the pump? You can't completely flush the Condenser, it'll still have some junk from the blown compressor in it, as well as the Orifice Tube. Flush the rest of the system before assembly.
When you get the pump, empty all the oil and measure it. Your system probably calls for ~8oz of PAG 46 or 100 (whatever). Put 4 oz in the compressor, turn it by hand to spread it around, preventing a slug going through it on startup. Make sure you have the 2-wire HP Cut off Switch in the back of it.Then put the other 4 oz in the Receiver/Dryer. If you only have 1 wire going to that old switch, ground it to the T-Stat housing and wire the new switch in series with the LP Cycling Switch. The old wire, when grounded will open the Recirc Door for inside air after 30 seconds when, the A/C is on its lowest setting and the fan is on 2 or 3. Here's a little drawing of how I did my 88. I also wired in a relay so I get full battery voltage at the Compressor Coil too. It shows (OEM) Cut Off at ~25 PSI
You must be registered for see images attach
Your Cycling Low Pressure Switch probably has an adjusting screw between the connector blades on your 88 but, if not, get one so you can lower the pressure shut off to ~20 PSI (i have mine set to 18). I'm getting ~35° (from my R4) with a 98° ambient temp.
@L31MaxExpress gets even colder air with another refrigerant.
Suck the system down to ~-28 or more " (a perfect vacuum is ~29") for about 1/2 hour or more, shut off the compressor, close the valves on your manifold Gauges, and let it sit for a while - I prefer overnight. Check to see if it maintained the around same vacuum. Then add refrigerant per manufacturer's recommendation (remember it takes less R134a), I usually use 3 cans, until you get it putting out ~20+ PSI @100° (my recommendation). Your high side s/b lower this way and still give you cold air.
Phew, sorry for the dissertation.