Displacement between mfgs means little.
Now displacement between divisions meant the world.
GM shared some sizes like the 400 but 400 was much different in a Pontiac vs Chevy.
When GM went to just using cooperate engines most of their cars lost their soul. The pounding roaring hearts under the hoods is what gave each car a different personality and feel.
Let’s face it the Olds corporate engine was never a desired engine in the Trans Am. Later on the 350 Corporate rendered the Late Trans Am just a styling exercise.
Many late Pontiac fans never understood this as they never experienced a real Pontiac engine other than an Iron Duke.