What year is your car? I don't believe the filter to breather deal came out FEDERALLY until about 67 and may have been 68. This may have been earlier in CA sold cars
I think you are correct that it was required in 67, certainly NLT 68. My CA built 65 wagon had the hose from the oil filler cap to the air cleaner; I would have to check my 65 literature but think it was mandatory for CA and an option for the other 49 states.