I don't live anywhere near there,however, I might give you a tip to help isolate it. First, I wouldn't discount it being valve train related...they can put out quite a knock under certain conditions. If you isolate the cylinders on at a time, pull a plug wire, if it's a bearing knock it will quiet down. Loss of pressure could be through a lifter issue, so that isn't neccesarily a bearing. Years ago, we used to check the
oil pressure bleed down ofter the engine was shut off. That gives an indication of the bearing condition. If there is another problem creating a loss of
oil pressure, that wouldn't neccesarily be an accurate test.