If you read his thread when the sump got damaged, he was advised to change the shells.
These engines simply cannot take any oil starvation.
How did the garage check the shells? No decent garage would 'check' shells. If you have taken an old shell out to look at it, bloody renew it!!!
I didn't read the original thread when this happened Mitch.
In answer to you question "How did the garage check the shells?" I would imagine that they took the big end and main caps off, checked for wear and scoring, used a Vernier Caliper to check the thickness of the bearings and Micrometer to check ovality of the crank before replacing and re-torqued the bearings. Just a guess mind.
But that ship has sailed. Now we can help this guy out by offering advice, not mocking him
As you seem to be fairly knowledgable about this engine maybe you could tell him whether it is likely to be the big ends and mains that suffer most through lack of pressure or the small end bearings that are splash lubricated?
My advice is this; if you are willing to spend a bit of money on a "punt" then take the sump off, buy a new set of bearing shells, replace the knackered ones, put the sump back on and keep your fingers crossed. You can replace the mains by tapping them round without removing the crank; there will be a notch at one end of the bearing and you need to tap it round from the other end, sometimes turning the crank is enough to make them come out. Loosen off the caps but only remove one bearing at a time! I'm not familiar with this engine so I don't know if you can get to the outer journals without removing the crank. As I say "it's a punt" that could cost you a few quid if it's wrong.
If Mitch can confirm that it is usually the small end that is knackered then you are probably better off doing an engine change as it's a head off piston out job; it can be done in the car but there is no point as you'll have to do belts, pulleys etc anyway.