Adding a PCV system to a Y-Block is very simple it you avoid trying to re-invent the wheel.
I have converted every Y-Block vehicle I have had for the past twenty-five plus years. I use the basic system that came on the 64 Ford 292 trucks; Remove the stock road draft tube from the valley cover, held in place with a 1/4" bolt. Attach the hose adapter that came on the '64 292's, route the hose to one of the many vacuum ports in the intake manifold. If the '64 292 PVC is used, it can be threaded right into a vacuum port. On some engines, especially those with a 4 brl carb, a right angle fitting may be required.
If the engine has a crank case vent, usually on the lower left side of the block, it must be removed and blocked off. For originality, a block-off plate can be inserted between the vent and the block.
The oil fill tube must have a vented cap so that fresh air can be drawn into the system. The is no need to run a hose from the oil fill cap to the carb air cleaner. The hose is very common on factory systems, where-as they were concerned about filtering the fresh air before it entered the engine.
If a '64 Ford 292 valley adapter can not be found, GM used a similar adapter on the 63-67 SBC's. The Ford adapter has a longer hose pipe which turns up slightly, where-as the GM is rather short and exits the adapter at a right angle.
I have used a variation of this system on some 292's, running the PCV into a valve cover similar to the SBC's.. I use the GM PCV and valve cover grommet, locating same between two rocker arms, which provides room for a baffle that must be fabricated and installed, to eliminate oil from being drawn into the system.
In the past we found that the addition of a PCV tended to make the engine run a little rich due to the oil vapors, leaning the carb out a bit helped. Recently we found that the new fuels tend to be quite lean, therefore the carb on my '57 Bird had to be made a little richer, that improved performance.
I have attached a pix of the 312 engine in my '57 Bird.. looking closely you can see the PCV hose coming out of the intake manifold, adjacent to the oil fill cap.