2000 TJ: Low Oil Pressure After New Oil Pump

It's been a rough couple of weeks. Two weeks ago, my engine overheated
because unknown to me, my radiator was leaking like a sieve. I had
topped it off a couple of weeks prior, but when I opened the hood, the
tank was empty. So, after a trip to the dealer and $400 later, I've
got a new radiator. Since it was in the shop and I was due, I asked
the dealer to go ahead and change the oil for me.

Driving home the other night, I got off the highway and while waiting
for the light to turn, my oil pressure dropped down to 0, and the check
gauges light came on. So, I pulled over, let the Jeep cool down and
checked the oil levels, and everything was fine. After starting it
back up and driving for a bit, I stopped at a stop light, and the
pressure dropped again. Stick 'er in neutral and rev, and up the
pressure goes.

So, I took it back to the dealer and asked them to poke around. The
ascertained that my oil pump was bad and replaced it. After replacing
it, though, I was still losing pressure. They hooked a gauge up to the
block, and pressure was hovering below 10.

They are recommending a new lower block at this point because they
figure the bearings must be bad. I'm having a real tough time with
this because I have really babied this Jeep. Oil change with Mobile 1
Synthetic every 3000 - 4000, maintenance, you name it. Could it be
something else or am I screwed? It only has 129,000 ( mostly highway
).

HELP!!