I have never found the need to modify the valley cover on any Y-Block that I have put a PCV on.. I always place the PCV devise closer to the intake/carb.. The '63-64 truck adapter is a domed shaped unit that attaches where the road draft tube was, using a 1/4" bolt.
Some of the FE engines used a PCV that threaded into the intake manifold.. As it has already been written, make sure the PCV closely matches the CID of your engine.. i.e. 292 = 300/302..
The block off plate for the block breather is the same size a block off plate for a fuel pump..
Make sure that the oil fill cap is a breather type.. Fresh air must be able to be drawn through this cap into the block.. There is no need to use the Ford style of cap from the mid '70's, and later that had a hose attached to the carb air clearer..
I have a '59 Ford F100 4x up at our ranch in Montana.. It had a very good running 292 in it when I bought it at a farm auction.. With a little service work I drove it the 150 miles from the purchase point to our ranch... I had noted that the engine had a lot of fresh oil on the engine.. When I arrived at the ranch I noted oil had been blowing out of the fill pipe..
I cleaned the engine compartment up, went to town, 50 miles, and purchased supplies, valve cover gaskets a PCV, hose and a rubber groment for a valve cover.. I opted for a valve cover application because I could not find a '63-64 block adapter..
I selected a location on the right valve cover that was clear of the rocker arms, cut a hole large enough for the groment and the baffle, I would have to fabricate to cover the valve train side of the PCV.. The baffle was fairly easy to fabricate out of light sheet metal. I pop riveted the baffle in place, painted the valve cover Ford red, installed new McCord cork gaskets and assembled everything.
The problem of the engine throwing oil out of the fill tube, etc., was solved.. The truck has been working on the ranch for over ten years with just a few minor repairs... Not to bad for a $400. truck and an afternoon of work...