It's one of the thousands upon thousands of federal BS laws. You can't put an engine older then a car into that car, supposedly for emmissions related reasons, but I personally think it is just to keep people from building fast cars. Many of the things we do to our cars are illegal anyway, and most inspection stations are not going to check on the casting date of your block (unless you live in Kalifornia ) I don't know how things are in Miami, but nowhere I know of in the state of Florida gives a flying f*** about what you do to your car.