How right you are!! The oil cavitates at the rear main but it gets enough as is does to keep it alive. When you lower the pressure (and use lighter oil) the cavitation is reduced, not eliminated because the rear main with it's restrictor installed acts like a dam. Your analogy of the oil is also dead on!! What it all adds up to is in a high rpm Cleveland no more trouble. A much simpler solution is a new Buttermore block with the revised oil system!