Tommay11 is correct in that cleaner emissions are a bonus of the PCV system. Many people misunderstand that this is its primary purpose. In fact, its primary function is to evacuate blow-by gases from the crankcase. This was formerly done with road draft tubes, but a PCV system is much, much more efficient. Without a way to evacuate these gases, sludge and dirt will accumulate much faster. The gases themselves are flammable, being full of unburnt hydrocarbons. Crankcase fires are even possible, though rare, when accumulated gases are subjected to enough heat and pressure. In a nutshell, the PCV system protects your engine and keeps you from having to change the oil all the time.
The spacer you describe removing sounds like a Boss 302 spacer. Stock aluminum 1" spacers with the correct PCV port are readily available. I got mine from NPD, but I'm sure they are available through many other vendors as well.
'65 Coupe, 302, Autolite 4100, C4, 2.80
'72 Grande, 351C, Motorcraft 2100, FMX, 2.75