Would love to see the "recall" for removing federally mandated smog equipment. Do you have a copy?
"Extraordinary claims require extraordinary proof"
I think that you are making a couple of incorrect assumptions. First, it was not a "recall," which is why I put "recall" in quotes. Second, emissions equipment was not "federally mandated" for cars manufactured before January 1, 1968. This can be confirmed from existing law in the form of the federal regulations regarding importation of motor vehicles:
"19 CFR § 12.73 - Importation of motor vehicles and motor vehicle engines.
(e) Exemptions and exclusions from emission requirements based on age of vehicle. The following motor vehicles may be imported by any person and do not have to be shown to be in compliance with emission requirements before they are entitled to admissibility:
(1) Gasoline-fueled light-duty trucks and light-duty motor vehicles manufactured before January 1, 1968;"
For cars made prior to January 1, 1968, what the Thermactor setup was addressing was a California emissions program. Also, California vehicles from model year 1975 and older were later made exempt from the smog requirements. This has, in part, been attributed to the counterproductive nature of the older smog setups.
There are references if you perform a Google search. Here is one specific to 1966 Mustangs with California emissions:
https://www.vintage-mustang.com/threads/taking-off-thermactor-system.539287/"I deleted my Thermactor system when I rebuilt the engine and restored the car. The system actually increased NOX emissions and there was a NOX retrofit program here in CA several years later that attempted to address the problem. Ford produced a special plug for the air tube ports in the manifold. If you install the Ford plugs, you simply need to remove the components. The smog pump acted as the belt tightening device for one of the belts IIRC. When you remove it you will need a different belt."
By the way, the oft quoted knee-jerk statement: "extraordinary claims require extraordinary proof" makes no sense in this context. A quick Google search will show that none of this is reasonably in dispute. The only justification for the Thermactor smog setup is the concours standard that requires the car to appear as it was when originally sold.