It IS a "smog era' car. By 1975 all cars had catalytic converters installed on them. In the state of California all 1976 and later cars STILL have to pass a bi-annual (every other year) smog test in order to get your tags.
There were also other federal regulations like the 5mph impact bumpers foisted on cars around that time. And compression ratios began to drop in the early 70's. So no,it wasn't a good time for muscle cars.
Most of the smog junk can be taken off now as most states have exemptions for classic cars,but it will always be a smog era car.