Thank you again Jeff, so I can safely chase down a smog equipped engine then, with out a doubt?
Always can be doubts but IMHO the chances are very very good that your car (lacking any evidence - and your original engine is not longer around) chance that yours came with the Thermactor system.
If I find a smog engine, I am of the Understanding that I can plug the exhaust ports that the air was pumped into and run the engine as normal without the smog gear attached? does the carby need to be different or will it operate correctly with a carby that was set up for smog equipment?
Anything else that would need to be altered (obviously the pulleys etc (mine has air and steer)
Kind of confused - in the first post you wrote
.............. I want this vehicle to be as precise as possible to how it would have been as it was sold new.
Now it appears that is not the fact.
So you want your car to appear that it had Thermactor on the car but you/or someone removed the system?
If so how far do you want to go? Replace the heads, alternator brackets and pulleys?
Your not likely going to have a major issue running the Thermactor distributor and carburetor without the system working though I had driveability issues when I've tried to remove the system on some cars in the past - but it was just likely me
The individual plugs for the head will only apply if that it the style of heads you find for the dates given. Mid year they also started using the internal Thermactor design on 289's so there are two somewhat different systems used during 66.
I guess the problem is the same as it always is when you start modifying these cars - how far do you want to go and where does it end
For me - I'ld just get a system and put it on. Will make the car unique