You'll also need a non EFI distributor... What happens is that the car runs better!!! The old crossfire units were far from being one of GM's better ideas... You'll also have to do away with the high pressure fuel pump in the tank and go to a low pressure in tank pump, electric fuel pump mounted externally, or a mechanical pump on the engine.... Pull all the wires back and stow them someplace neatly in case some dummy would someday want to bring it back to original.....