The laws in most emission testing states, except CA, which has it's own weird rules, is any powertrain the same year or newer can be transplanted. Usually with a matching transmission as part of the emissions package. If a manual was available behind that engine, you can use a manual trans. It has to meet the emission requirements it had in it's original vehicle. ie, if it's a 2014 engine in an 86, it has to meet 2014 emissions. Besides CA, I hear AZ is getting stricter and the NE like NY, NJ, and PA are notoriously difficult. I live in a red state. Most of them don't care what you do. Since your truck is an 03 you are pretty much stuck with an L$ engine. Last year of the SBC was 02.
Where you trying to register it?
Some Californians register their hot rods in NM.
Where you trying to register it?
Some Californians register their hot rods in NM.