Is your block a one piece rear main seal block?
Make sure your oil pan is fitting good at the rear main cap and also the timing cover seal. Do not accept the fact that they are new and should be fitting well, some pans and timing chain covers are made in China and don't fit worth a flip.
Use the one piece FelPro (don't accept any other brand) oil pan gasket and install it DRY, not even silicone in the corners it's not needed.
If you have a two piece rear main seal you might try installing the seal so it's mating line is 180 degrees to the main cap/block mating surface.
You said you have a PCV valve in the line that goes to your air cleaner, that is not correct. The PCV valve is installed in a manifold vacuum line, usually from the base of the carb or a fitting on the intake manifold. The PCV filter in your air cleaner goes to a hose that comes from your valve cover. The way it operates is a vacuum is pulled through the PCV valve. Negative pressure in the crankcase is then equalized through the tube into you air cleaner.