I am not 100% sure on this..but here's my take.
For it to be a kit car,it would need to be registered as a kit car or something along those lines...to be smog exempt.
If it still needs to be put on the smog machine,you would need all of the original smog equipment from the car that the engine originally came out of.
Where I live,every car made before 1980 is basically emissions exempt..or something like that.Anything else,including kit cars,need some sort of emissions equipment,and still need to come up clean on the emissions dyno.
I'm sure if you just show up with a civic and claim it to be a kit car,the smog guys will call your bluff and run the vin (if it has one)..
The jap cars dont have vins and are rhd..so it is feasable for those to be considered a kit car.
Hope that helped you some.