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you left out important variable out of equation. Those "exceptional" NA engines with even higher specific power output per volume, were way less strangled by modern eco emission standards. I'm certain that be it now, those wouldn't be that "exceptional". If even Honda, maker of (in my eyes) best inline-4 engines "gave up" and went for turbo in latest type-r generations, should speak a lot about it. Now only supercar makers can still afford to develop/make "exceptional" NA engines comparable to those in past.

Then you'll be wanting an automatic gearbox and a truck engine. Not especially sporty, but you can spin the tyres right off! I expect you could get a boxer diesel in the engine bay if you really wanted... however I agree that low torque performance engines can be hard work, and not especially good at daily use, having owned a series of high revving engines. On the original topic @Jay Bamrah it is disproportionately expensive to tune for NA peak power without increasing cylinder capacity. The "famous" NA engines all have ambitious red lines, complex adjusting intakes, fully variable valve timing and really strong engineering around the camshafts. That stuff doesn't come cheap! If you soak in some of the press around engines like the Porsche block in the 911R, Gordon Murray's Cosworth unit, the Ferrari 458 V8, Honda's F20C, Mazda's Renesis you really get a sense of how hard it is to get more power when you can't make the flame front any faster. Anyone (sort of) can add boost pressure and fuel, but it takes bespoke engineering to raise the redline usefully and not completely ruin the engine for regular use. The FA20 is a pretty good but not exceptional NA engine at just under 100 bhp/L, but it's a much easier normal drive and more efficient than the F20C that just about squeaks 120 bhp/L.