But, that's not to say that if your state does not have a visual check component of the inspection, then maybe. All depends on how close you get the fuel mapping, that you are running an O2 sensor in a feedback loop for good emissions, and have a functioning cat.
There is no reason you couldn't make a 77 CLEANER than stock utilizing aftermarket EFI, but in CA, there's no way it would pass unless you had ALL the stock components installed. On a 77, that might be an interesting challenge, though---but the coil packs of something like SDS or TEC 2 would be a dead giveaway that something isn't kosher.
I had a very in-depth response and it got eaten! ****!
1) See what your testing requires. If it's idle and 2500, then you should pass cleaner than stock with just an O2 Closed-Loop operation and a functioning Cat.
2) If you have dyno testing, you will have to have EGR to control NOx. If you understand when the STOCK computer injects EGR, then copying that control scheme should get you in the area, but you may want to dyno it yourself and get some five-gas readings.
3) A Turbo emits less-NOx under off-boost conditions anyway, due to lower compression.in other words:
TURBOS ARE GOOD FOR THE ENVIRONMENT (eat me, Greenpeace!)
4) A clean car in most cases makes MORE power than one that's not! Performance is clean! You do not WASTE fuel by just dumping more in the combustion chamber, therefore you are cleaner. Remember the stock EFI was a tad RICH on the bottom end, and leans out on top during WOT. Just because rich makes drivability nice--most people get their driving done below the max RPM's. Performance calibration lets you carry rich all the way to the top, but for emissions testing purposes, you can actually be CLEANER than stock in the area of operation where you drive the car 95% of the time!