Emissions crap on a 74

In CA the '74 models and older don't have to smog check. I had to smog my 318 Satellite once. It failed the visual because when he revved it, the EGR linkage didn't move. I chased it for a couple days even replacing the vacuum amplifier with a couple borrowed from the boneyard. Finally tracked it to a small timer on the firewall that was meant to keep the EGR from operating within a certain period of starting the engine. I put a small tee in the vacuum line between that and the EGR to quietly bypass it. The EGR worked as advertised and it passed. I was told that timer was only installed for a portion of that one model year. Others here can likely confirm of refute that.

Definitely get rid of the seatbelt interlock. Mine was intermittent. After taking it out I opened the control box to see what was in there and a portion of the circuit board was burned. Simple to bypass in the wiring.