[71cadc10]

I've never tried to put them in with the crank in the way...I guess it's possible but would be tough.
If that cam bearing walked out far enough it likely was rubbing on the lifter, which will put a lot of soft debris in the engine. You'll see a nice half-moon shaped notch in the side of the bearing if the lifter rubbed it.
I've had this happen...oil pressure drops too if it walked far enough to uncover the feed hole.

If you pull it apart to inspect, probably a good idea to check the main/rod bearings I think. Just keep all caps orientation and locations, and you should be good to re-assemble it. Replacing the rod bolts with new is often done at this time. Main bolts are not torq-to-yield so you don't have to do new main bolts.