Thanks for the responses. It appears I wasn't as clear or as detailed as I should have been. Let me clarify:

After installing all the new components, I connected my gauges, pulled a vacuum for 30 minutes to get the air (moisture) out, then pressurized the system with pure argon (since I don't have access to nitrogen). I left the gauges on the car and left the car to sit for 24 hours. I returned, found the pressures to be exactly the same as when I left it (I put little marks on the gauge face cover to indicate position). I concluded there were no leaks in the system, so then I pulled a deep vacuum for 90 minutes (down to 27 inHg) via my electric vacuum pump. Not needing the car for transportation, I left the gauges attached for those 5 days and let the car sit.

When my R12 arrived, I pulled vacuum for 10 more minutes, attached the cans to my gauge set (that's what I meant by "attaching my gauges" in my first post), and filled the system with refrigerant. My gauge set has valves used to open and close the lines, so I used them to close the system off during can changes. I even purged the fill line with the tiniest amount of R12 by cracking the screw-on fitting on the gauge body to expel any incidental amount of air in the line before opening up the valve to start the flow of refrigerant into the low-side (suction) line.

From what I've read on this forum, I believe I've followed the correct procedure with my A/C evacuation/filling, but correct me if I'm wrong. At no point was there any refrigerant in the system while it was under vacuum. What would be the purpose of having the compressor INTENTIONALLY leak refrigerant under any condition? Whatever the reason, that's not what's happening to me. I'm just curious.

My system is perfectly sealed. I have no leaks, and my refrigerant is all intact. At this point, I'm starting to suspect that perhaps my new condenser is sub-par, given the results.

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1984 300SD
351,000 miles