I don't consider myself an expert by any means on the subject, but I can tell you this:
PCVs went nationwide in 1962. GM offered PCV technology free of royalty to the US automobile industry. Engines were PCV equipped without any legislative requirement!
In 1968, the EPA enacted
nationwide standards for tailpipe emissions. Typically, by musclecar standards, 1971 is still a good year, but by 1972, emissions started bogging down performance.
My dads 1975 GMC truck was well-stocked with emission reducing devices. This is the first year
catalytic converters were widely installed. I think you're ok with a '70. I'd steer away from anything after '72.
Bill
