Hold on you guys. We need to know which county he lives in first? Some counties don't require emissions testing. OP, if you are lucky enough to live in one of those counties, you're golden. If you ever move from that county, you'll need to make sure it will pass emissions.
However, if you live an emissions testing county, then you have to stick with what the truck came with, or was a factory option, and then you need to have all of the parts and pieces from that type trim level to make sure it passes. So basically you'll need the entire truck to get the parts off of, to put on to your truck. Save yourself the headache if you do live an emissions testing county, and just stick with stock, or upgrade to better breathing. Such as vortec heads, better flowing exhaust, etc to gain some ponies but still pass smog. If this is for your V30, the smog requirements are way more lax than if it was a half-ton truck.
I have a coworker that has an '81 C10 stepside. It came factory with an L6 and he swapped in a 305 or 350 v8. V8's were an option, but had single exhaust. He had dual exhaust put on, and swapped the intake, carb, air cleaner, etc. It wouldn't pass. He had to put single exhaust back on, but went with 3 inch and now gets horrible mileage and lack of power from what it would have had stock. Still wouldn't pass, even though the numbers were good. Visual, fail. He re-did the hoses, wouldn't pass. Again and again, wouldn't pass. Finally took it to the Referee. He had the wrong charcoal canister, and hose routing. The Referee told what he needed, and it finally passed smog, but it now has a new VIN to show it as a v8 truck.
So it can be done, but you have to have all of the correct parts for that year and GVW truck, otherwise you will not be able to register it.
I personally have swapped on vortec heads on my '81 C20, but everything else is stock. It looks like a factory engine bay, the engine runs really strong, and the numbers are always good. But it being a C20, I can do whatever I want to it, except an engine swap to something couldn't have as an option, unless I want to also upgrade the emissions, which I do not.
