I just finished my son in laws 99 chrysler 300m with 3.5 engine. May be the same problem your having. "No oil pressure to top of engine -lash adjusters clattering - and oil lite coming on while driving."
The dealer offered to do a hot flush, then claimed the engine and car not worth the work. They should have known the issues with this engine and relayed that back to the customer. I dropped the oil pan and found sludge in the oil pan, oil pan tray, and a thick coating in the oil pickup screen. Main bearings were barely worn, but the rod bearings were badly worn into the copper backing. All this started as a "sudden" problem with no indication of impending failure.
The PCV valve is under sized as the engine produces less blowby (when new) than most engines. When worn, the PCV valve cannot handle the blowby volume and sludging occurs. The oil pick up in the bottom of the oil pan is likely plugged with sludge, restricting oil flow. Along with this, the crank throws are offset (potential oil flow problems when dirty, sludgy or low oil press) and the rod bearings are likely worn.
Ask your shop guy how much crusty oil sludge was present under the valve cover and figure about the same or more in the oil pan. Your engine was disturbed and you have either flushed or loosened sludge particles into the oil pickup.
Cost of the repair parts came in about 150$. Add 1500$ - 2500$ if you have to pay for labour.
In other research there is (was) a class action lawsuit over sludging issues.