Remember all these engines are mass produced. A cam grinder can tailor a cam to your engine, gearbox, diff ratio, weight an intended use. GM or anyone else used the same cam regardless of whether it’s in a manual ute with a 3.55 performance rear axle with a single exhaust or in a GTS with dual exhaust, auto and 2.78 rear axle, or a lighter Torana.

With a roller cam you get more total air as the valves open far faster, thus they don’t need the same aggressive profiles as a flat tappet to get similar power delivery thus normally meaning an increase in lower rpm torque. There is lots of articles on US websites where they get old engines like 307 or 350 with good compression from wreckers dyno them as they are then put in modern cam profiles and induction and get really good power. Even a modern flat tappet hydraulic does wonders compared to the stock cam. I’ll find a couple.