This must be the year of PCV systems since I just got done commenting in another forum about converting to PCV.

The way you've described your plan for the positive crankcase ventilation (PCV) system won't work well since you mentioned having three breathers (filler tube and one on each valve cover). If you don't have any qualms drilling holes in both valve covers (or if the holes are already there), the ideal configuration is to have the fresh-air intake breather on one valve cover toward the end (fore/aft) and the PCV valve on the other valve cover at the opposite end (fore/aft). Ideally, the fresh-air intake breather will connect to inside the air cleaner for filtered air, although you can use a high-quality stand-alone breather with an integral filter element but will need to blow out, wash, and possibly oil that breather filter element for routine maintenance. The PCV valve must attached to manifold vacuum either by using one of the intake manifold's vacuum ports, a large port on the carburetor (depending on what carb you're running), or using a carb spacer with a vacuum port. It's best practice to not branch off the power brake booster if equipped since that should be a dedicated circuit to the booster. The last piece is to use an unvented cap on the oil-filler tube rather than a breather so fresh air is forced into the valve cover breather, flows down into the lifter valley, moves diagonally across the valley collecting gas vapors, and exhausts the vapors through the PCV valve into the intake manifold. Leaving the filler tube vented will allow air to draw from both the filler tube and valve-cover breather, which will greatly decrease the air velocity and impede the system in flushing out the gas vapors before they have time to condense into the oil and/or embed themselves into existing sludge.