Is 350 rocket engine a small block in 1980 Buick Riviera?

No, a 350 rocket engine is not considered a "small block" in the context of a 1980 Buick Riviera or most other GM vehicles of that era. While the displacement is relatively small compared to some engines, the Buick 350 was a *big-block* engine, sharing the same basic architecture as other large displacement Buick V8s. The term "small block" generally refers to GM's smaller V8 families like the Chevrolet small block (e.g., 283, 307, 350).