Oil Dip Stick blowby ??

Check where the hose from the PCV goes into the base of the carb...... sometimes that point gets plugged up with hardened oil crud and that has to be dug out and cleaned out. And make sure the PCV hose is not collapsing....using heater hos will not work! It needs to be PCV hose, which is designed to not collapse with a vacuum inside. It may well be worn rings and pistons, but there are a few things to go through first...

Low oil pressure could be just due to a good heat soak of the engine getting the oil hotter than normal, thinning it, and that produced the lower oil pressure. How far and long do you normally drive?