Below is CA Vehicle Code 27156 link that is referenced in the post above, just one of 42,277 CA Vehicle Codes. As mentioned above, seems to pertain mostly to smog equipment only, and not modifications to the actual engine. However, throwing in a 408 aluminum block and hooking up all the required devices may not work too well...hee, hee, hee.
All you other non-CA boys, watch your legislation and legislators in other states, as 42,277+ vehicle codes could some day come your way. CA is the leader in this type of crap, and others often look to what CA is doing to create their own laws to make their own jobs more secure with additional laws that need government people to enforce them.
Happy motoring & watch your rear view mirror! Even with a 408 block, it is difficult to outrun a Flat Foot helicopter.