Edit:  title should say this is why clean is important....

This engine has never been started.  You can see the piece that caused it stuck in the babbit near the part line. Always clean all oil passages before assembly.  I do pressure washer, then compressed air, then solvent, the more compressed air.  Apply assembly lube with a bare finger...that way you can feel if any grit made it's way onto the bearing or into the lube.  Wipe down all surfaces with a rag, then with a bare finger....fingers leave no lint and find stuff that rags and gloves don't.

Good tips,, you didn't mention using proper sized brushes for all the oil galleys and passages during the cleaning process.

I have never felt the need to remove the block from the stand to install the cam, but do usually install the cam first, when I can use my finger through the cam bearing to support the rear of the camshaft to align it through each bearing.

Many people don't have a proper cam bearing tool to install the bearings themselves,, but certainly that is the best way to do it. 

I would have thought those wackers would have roller bearings.

That's funny