Well I found the issue, right under my nose. A simple $3 valve core for the high pressure line. I ended up replacing both the high and low side. After 1 hour on the vacuum pump, I refilled with ester oil and about 900 grams of R134-A. I forgot how cold the A/C can get in this thing.
On to the next project – front wheel bearings. Not bad for 135K. Most of these go before 100K. The power steering pump will have to wait.