I guess it depends on what era you're talking about. Nowadays, an EFI 4cyl could be HP. I guess if you're talkin about the muscle car era, I'd say a good induction system, "a little more" cam, better cylinder heads, decent exhaust, maybe more compression than grandmaw's car, maybe a looser ignition curve.
It's claimed and famed they never made a "HP" version of the LA318. But, they added a 4bbl and 360 heads, so by your description then they did make a HP LA318. I could agree with this.