A few things to report after a few days of driving...

1.  The AC 134A retrofit is finally working as it should.  The AC is
entirely acceptable (fine in the front, probably too cold for the rear
pasengers) now that I've got the front rad fan on "medium" speed as it
should with the AC on.  I've never had the rear fans working on the 3rd
speed until now, and as expected, that's the perfect setting.

2.  Stock brakes on the 90 Westy are actually quite good if they're in good
shape.  With the front rotors/pads/bearings just replaced (and rear
drums/shoes/bearings 10K ago) I've noticed a significant decrease in
braking distance.  I was contemplating an upgrade, but given a properly
functioning stock system, I don't feel there's a need at all.

Now that everything is fixed, it's time to sell it quick :-)