Not to avoid troubleshooting your rings. But.
I presume the LC8 has smooth rod & crank bearings. If they are loose enough, the big end of the rod bearing can spray oil onto the cylinder walls, overwhelming the oil ring. No suggestions on how to determine that w/o a tear down.
Does this engine design have a cooling jet of oil that sprays the under side of the piston? If so, how is this regulated?