1971-1973 Buick Centurion Even rarer than the Monte ... Also luring customers into the showroom was a 455-cubic-inch big-block V-8 good for 330 hp when the Riviera was ordered in GS trim.

The Buick 430 would continue in use through the 1969 model year, and in 1970 both it and the 400 were replaced by a bored-out ...

There were 2,472 examples of the Stage 1 455-cube GS ... That’s better than the Buick’s 3.42:1. Still, the big-block GS455 also has a few extra horses and lb-ft tucked under the hood: 290 ...