i have scored really nice motors in the past that somebody thought was toast. i bought a 60's era 427 out of a vette . not the big hp motor so calm down . i put it on a stand and checked compression . good all 8 holes . the guy couldn't tune so it was running really fat . smoked a lot . likely washed down the cylinders . i put ti back together with new gaskets and seals. put a good tune in it and was good to go. within a few hundred miles the cylinders cleaned up and seated .
a pcv valve wont do diddly on a fat motor pumping up the crankcase . i use the moon breathers on every build and my motors dont leak for a good while .