In order to keep things in perspective, we need to keep things as apples to apples and oranges to oranges. I’m a real statistics nut when it comes to engine power and torque figures and remember them throughout history like a sports fan might recite batting averages.
1971 was a transition year and in many cases both the gross and the SAE net figures were given.
Let’s take your 302. In 1971, the last year it was rated in gross HP, it made 210 gross HP. Free breathing on an engine dyno, and sans any parasitic accessory drag. That same engine dyno rated ( not a chassis dyno showing rear wheel hp…that’s a whole different enchilada ) at 150 NET HP. All the accessories, breathing through single exhaust. I’ll bet a set of dual exhausts would boost that to about 160-165, but given the same exhaust configuration, both engines would give the same SOTP ( seat of the pants ) feel in the car whether it’s rated as gross or net. Peak power was 4000 to 4400 rpm. Not high, but typical for a base 302 with 2 barrel carburetion.
Next year in '72, the compression ratio was reduced from 9:1 to 8.5:1. Net horsepower now at 141, though I doubt that half point compression reduction accounted for the loss of 9 net HP of a small engine like that. I’d chalk that up to more conservative tuning for emissions reduction. Even so, unless one winds it over 4000 rpm through the gears, most wouldn’t really notice the loss anyway; it would still have a night torquey feel at more sedate driving conditions.
By 1977, things took a dark turn. More restrictive head/combustion chamber design and even more mild camshaft timing for emissions reasons, and now that single exhaust is also equipped with a restrictive catalytic converter. Those early converters ( 1975 to 1983-ish ) were the next worst thing to having a potato wedged in your exhaust system. power was ( depending on the vehicle ) 129 HP, or in some applications, 134. Strangled as it was, it made its peak power at 3400 RPM. Though still possessing a decent amount of off-idle and low end V8 torque, it was also working against insane high rear axle gearing.
Oranges to oranges, in the realm of high performance, the net ratings were mainly just paper, but the lower compression caused a required shift to milder cam timing. Decent runners they were, but by the time catalytic converters hit in '75, forcing all single exhaust, high performance free-breathing engines were dead anyway.