How much power do engine mods yield?

First up, I would like to see which OE chevy heads flowed 280CFM,even modified.Like
none.Even admitted by their most avid supporters,an "all out" unit from the day is
lucky to post 250CFM,backed up by Smokey Yunick himself.I again take issue w/
the notion that the slanty head sucks,simply because it doesn't.Yes, the bore is a
definite restriction,and if ma mopar had cast a little more meat on the long side of
the pocket,things could be better.But valve size isn't the only factor,and the shape
and orientation of the slanty port has a superior discharge coefficient compared to
other ports w/larger valves, and swirl properties as well. The small bore/chamber is an excellent deterrent to detonation, as is the spark plug location,even w/o a
"squish" to speed up combustion.Is the 225 ever going to be a high rev monster?No.
But name how many 400HP 302 fords&chevies are running around w/o bigass cams,
steep gears,and loooooose converters,like none.Of course excluding anything with
modern variable intakes&cams etc.,which is kind of like cheating,but we'd all take a
retrofit system in a second if an affordable/viable one ever appeared!
Secondly,I'm done to death w/the "torque vs. HP" canard, there is no such thing.
More torque IS more HP, and so is the same torque at a higher RPM,they can't be
exclusive.The question is not improving torque, but efficiency at the desired RPM
range you wish to operate your engine in.You either want more efficiency at low
RPM,or higher RPM.Some improvements benefit BOTH,which are the ones you
really want.Such as compression,larger valves,and any fuel/ignition optimization,
along with exh. improvements.High RPM's go faster,but generally require sacrifice
in a whole bunch of areas,and there is a limit to whats tolerable for everybody.
Whats yours? Sounds like You know where you're headed,so best of luck to you,
:coffee2: