Looks like old crusty had a fast swipe to clean up the rust on those walls..Good call to get that block checked out hoping its not hiding something...l would be checking that crank out for sure seeing to top sludge.
One thing I learned about PCV valves. Years ago my son had a 86 Crown Victoria. It would belch out oil smoke from time to time. Turned out the cure was a genuine Ford PCV solved the problem. One of the mechanics at the local Ford dealer told me to try one.