My state, NJ inspects emissions for vehicles with normal registration, regardless of age. They still pop the hoods on older cars, not every time but often during an inspection. You can get QQ plates here to be extempt from testing, not from obeying the law, but they have restrictions that makes them just as big a pain as going though inspections.
As for the carburetor LSX kits, they are intended for pre emission vehicle retrofits. Such as installing a LSX into a 50s or 60s car since they predate low emissions. However in an emissions era car, 1970s to present there are legal problems. The newer the car, the stricter the emissions laws are for it, the less freedom you have to mod it, yes it sucks.