When you tear the engine down you should check your oil pump housing. The metal chips in your filter passed though your oil pump on the way to the filter and may have opened up the clearances. Ultrasonic cleaning is the way to go. I rebuilt an engine with a failed IMS bearing (single row) and spent a lot of time cleaning with solvents and still found some chips in the pan after the rebuild. I went back with a sealed greased steel bearing (partially due to bearing contamination concerns) and modified my IMS to keep the grease in the bearing. I've put about 2000 miles on the rebuild, with plenty of redline, heck, almost always redline, and the bearing has held so far. The bearing will be pulled after 15k miles, and if the engine has no sign of metal in the oil an open bearing will be a possible replacement. If there is any metal in the oil it's likely to tear up an open oiled bearing. I looked at using a roller bearing but was concerned about shaft alignment with the rollers after reading bearing manufacturers data. Roller bearings require close alignment, something the designers of the M96 were not designing to as they used a deep groove ball bearing which is relatively insensitive to shaft alignment. I posted my rebuild on this forum, though not as good a job as you are doing.
