One of the overlooked things about swapping in a newer engine into a older car is emissions legality. Basic thing is when you install a newer motor into a older car, the car must now meet the emission standards of the engine's year. So install an 2007 LS into a 87 G body, it now must meet 2007 standards.
I can't find too much about what emission systems LS motors come with but here is what I found. Early LS1s have EGR and smog pumps which you need to keep for a legal swap. Later factory LS motors don't seem to have them. All LS motors have cat converters and a EVAP system that includes purge and vent solenoids and a gas tank pressure sensor you need to install. Carburetor retrofit kits for LS motors are illegal for emission era car swaps like G bodies because they disable the OBD2 emissions system. You also can't delete the rear O2 sensors, got to make them fit to be legal. Last thing is under federal law, G bodies are never exempt from obeying emission laws, regardless of what your state says or how well they enforce such laws or perform inspections. It's your choice and own risk of a $2,500 fine of which way you want to go.
I can't find too much about what emission systems LS motors come with but here is what I found. Early LS1s have EGR and smog pumps which you need to keep for a legal swap. Later factory LS motors don't seem to have them. All LS motors have cat converters and a EVAP system that includes purge and vent solenoids and a gas tank pressure sensor you need to install. Carburetor retrofit kits for LS motors are illegal for emission era car swaps like G bodies because they disable the OBD2 emissions system. You also can't delete the rear O2 sensors, got to make them fit to be legal. Last thing is under federal law, G bodies are never exempt from obeying emission laws, regardless of what your state says or how well they enforce such laws or perform inspections. It's your choice and own risk of a $2,500 fine of which way you want to go.