PCV was required in California staring the in the early 1960s - so, Gerald Brown Sr. times. It was the first and so far only major smog control program that applied to in-service engines; subsequent requirements applied only to new or remanufactured engines. Yes, my Dad was required to convert the '57 Chevy to PCV - essentially, a hose replacing the crankcase breather and a PCV valve added to the valve cover. It produced a really significant reduction in emissions at the time. It was claimed that it plugged up engines, but it actually didn't if done right - our Chevy never had an problems attributable to the PCV.

Reagan (Governor in 1967–1975) presided over the first major round of EXHAUST emission reductions in California. Including the first version (my family's 1968 Dodge got the benefit of those) that caused a lot of engine problems and actually made smog worse - it produced a modest reduction in ROG by fiddling the timing, but the resulting heat made NOx worse, and things changed again in the early 1970s to deal with that (EGR valves and exhaust air injection came from that, which really did mess up engine operation and totally kill fuel economy, at the time of the first gas crisis).

An interim step effective in 1971 in California was a mandate to build engines to be able to use 87-octane unleaded gas; it was hard to find at the time, and not cost-effective, so nobody used it. But the mandate resulted in a bunch of former hot-rod tricks coming into general use to minimize damage unleaded would do to the valvetrains of the day. My Opel (1971) was the first Opel to meet that standard, and the 1900 engine I had produced about as much power as the 1600 of the previous year did; reduced compression ratios do things like that. It was essentially the beginning of prep for catalytic converters, which required unleaded gas and were clearly going to be needed at some point (that point ended up being model year 1975).