Also, keep in mind, that a lot of times, the EFI is tied in with a lot of nice little computerised options. Being an 84, that is going to be a lesser problem, but if you want to get the most bang for the buck, keep the EFI, chip that sucker, the MSD box would be a good idea, and keep the Crossfire systems parts in case you decide to sell the car to a collector later. Thus, my two cents.