I have a classic GMC motorhome from the '70s with the Olds Toronado front wheel drive power train. It had a carburetor, but like all carbs, it ran like crap.
So being an Ex-farmboy shade-tree mechanic with 45 years in mobile electronics, I switched it to Electronic Fuel Injection (EFI) with Electronic Spark Control (ESC). Now it starts instantly and runs smooth like a new vehicle. No more run-on dieseling or cranking forever, then belching black smoke when cold or hanging on high idle forever.
It now has modern features like Lean Cruise and Deceleration Fuel Cut-Off. The EFI system I used is all GM from 90's era GM light trucks and vans. Its not an aftermarket kit.
My Province got rid of vehicle emissions testing years ago since almost all vehicles passed easily. But I know owners of GMCs in California have to limp along with the old technology carbs, even though EFI conversion would be cleaner.