The condenser core is woefully inadequate for the system.
This was confirmed by an AC tech guy that I knew.
If you're going to drop serious money to fix the system, try and get a custom / bigger condenser core.
At the same time, you're probably need a stronger / larger fan.
Most of us go electric fans anyways, so this might be a moot point.
When I had my stock AC working, I think the FC was the ONLY car that actually got HOTTER when you turned on the AC...
-Ted