Wow, thank you all for your input.  This is exactly the kind of wisdom
from the field I had been hoping for.

>Regarding the SS pipes their joint isn't over the fuel tank it's about even with the fuel pump and easily accessible

Aah, excellent.  I have the original metal tubes, but they are in
rough shape, so I'm planning a coolant-drain weekend to take care of
all of this, clamps too.

I re-did the cold pressure test yesterday, and was down to "only" 5
drips, however, two of them, which I hadn't noticed before, were
coming from the radiator itself, where the tubes join the side tanks.
I have the 1982 diesel radiator (copper/brass), which I understand is
unique to that year, and NLA.  I saw some references to getting a
radiator re-cored, and I think I would lean towards this over
retrofitting a newer radiator.

Do any of you have any favorite radiator shops in the so-cal area who
might be able to do a re-core?

I'm trying to defuse all these time bombs and hopefully have some
adventures further afield, but I think I'm just surfing the tail end
of the bathtub curve.

Alex