California has a procedure to register a specially constructed custom vehicle and decide what smog regime you want to be under:
Per California Vehicle Code §4750.1, the first 500 program applicants in each calendar year may choose whether the inspection is based on the model-year of the engine used in the vehicle or the vehicle model-year. If the engine or the vehicle does not sufficiently resemble one previously manufactured, the referee will assign 1960 as the model-year.
The 500 person quota for this is usually filled on the morning of the first business day of each year.
A specially constructed vehicle (SPCNS) does not include a vehicle that has been repaired or restored to its original design by replacing parts or a vehicle modified from its original design.
Example: A Volkswagen "Beetle" with modified fenders, engine compartment lid, and front end, but still recognizable as a Volkswagen is not considered a specially constructed vehicle.
If your using a Spyder chassis that is still mostly intact and just modifying the body, suspension and replacing the engine, I
think you should be fine. About the engine...
You can put a completely different engine in a car and California will be totally fine with it as long as certain criteria are met:
- The engine has to be newer than the original vehicle or from the same year. You can put something from an '83 into a '78 car, even if the manufacturers are different.
- The engine has to have all the smog reducing equipment that it came with in the original installation. It also can't have anything on it that isn't CARB approved equipment (no aftermarket high performance air intakes unless they are approved).
- The engine and car have to be from the same or lower vehicle weight class. This means you can't put a truck engine into a car. This is a car engine so you should be fine.
- This has to be a road vehicle engine, no Volvo-Penta marine engines, ok.
- I also think if it was a manual trans car you have to stick with an engine that came with manuals.
These are all federal laws btw, but only California really bothers to enforce them.
Then you get referred to a special inspector "referee" who looks at your project to verify compliance and gives you a sticker that gives the smog check stations instructions on how to check your car. This will not be relevant to a diesel but if everything is done right you will get a sticker that says what type of engine you have and that it's legit.
Or you could register it in VA since you are legally allowed to live full time in CA and register a car out of state, if you are in the military. The advantage California gives you is that they don't really care what you do to your car as long as the smog requirements are met. There are no annual safety inspections.