This is not really helping you answer your question, but about 25 years ago after my first engine rebuild, I took the 428FE on the first real trip a few miles from home. And when I finally gassed it, the rear seal
oil seal popped out. Lucky, the hydraulic lifters quit and stopped the engine before any real damage occurred. Maybe an advantage of hydraulic lifters? I had to pull the engine anyway, so I was able to clean up with an empty engine bay. Over the next few weeks, I did feel guilty driving over the
oil streak left behind on the road. However, it did not look as bad as I thought it might after losing 5 quarts of
oil.