A letter to C.A.R.B. would be in order, to assure it's within the bounds of their rules. Last I recall, even if it WOULD pass the sniffer, it still won't pass because it has non-original parts and emmission control devices are rendered inoperable. The fact that it would be more efficient and pollute less means nothing to bureaucrats. They aren't interested in "right and wrong", all they care about is "compliance"...
'72 models, even when they weren't "exempt" due to age, did not require passing a sniff test at levels of catalyst cars. I left California more than 25 years ago, so I haven't kept up with the local laws like I used to.
Jim