The cat will do most of the work. If you have true dual exhaust and 2 cats, and the inspector is a stickler, it won't pass because because the car was never certified in that configuration. If your son will use a private shop for inspection, he should ask about these sort of details so you can sort them out before he brings the car in.
Thank you. I don't think my son will use a private shop. He told me they run a camera under the car and look for catalytic converter. My son built this engine and has concerns,due to the cam he put in it, that it will pass.
The picture you showed of your 660 choke a wee bit open.... my street avenger 770 shows the same, but the choke setting on the big dial is set to the middle, one blip of the throttle when its cold, sets the choke and off it goes to 1500rpm(holley setting), much too high IMO, so i turned the choke idle screw out 1/2 turn, slightly lower rpm now and the choke performs better for me.