This is where your thought process went off the rails. Barring any external rules, taxes etc, a OHV V8 will always have substantially more displacement in similar size and weight package. The OHV motor will be more bottom heavy (a good thing). The fact that a DOHC V8 has substantially less displacement per package is the reason the Mustang has been stomped on since the 4.6 GT unveiled in the 90s. A Lt1 can do 7 liters no problem and the Ford, well with BIG dollars into it can do 5.2. The LT1 is smaller and lighter.
In what power per displacement is not a designed parameter. Power per weight, power per external engine size, power per MPG, power per drivable torque, power per actual cost of manufacture, power to longevity. The canard of power per displacment is just that a strawman agument. My last B20 VTEC engine put out 275 engine HP from 2 liters. I've done K20 that do 300 complete drivable HP, 600 RPM idle engines, are they faster than a LT1? Nope. Why cause HP per CID is MEANINGLESS. HP and Torque per engine that fits in the engine bay is what wins races.
With the cam in cam technology, overlapped can now be adjusted on OHV and you can take a look at the HUGE jump in HP as implemented in the Viper. That is a single phaser and one cam vs upto 4 phasers and 4 cams.
Move more air are you kidding me. Why does the LT1 have WAY WAY WAY WAY WAY more and torque and flatter torque? Cause a BIG cylinder moves more air than any silly 4 valve design.
Lets play a little Gendanken Experiment: NA street HP: Ford it would be hard to get past the 5.2 Shelby at 526 HP, say the best you could do with aftermarket stuff is 570 HP, 440 ft-lbs. For the LT1 you can do a 427 running Victor heads and a big cam: 570 HP but 540 ft -lbs of completely flat torque. NOWHERE in the entire 5.2 performance envelope will it ever maker more torque than the stroker LT1 will make as a MINIMUM over its rev range. It is power under the curve that moves a car.
http://image.superchevy.com/f/120187...comparison.jpg
Ford has had so so so many redesigns of the original mod motor, and finally after dual inject design number dunno 10? They have an engine that makes the same HP as a OHV engine with WAY less usable torque. Great. GM could implement cam in cam technology yesterday and bring the LT1 to 500 HP and an even flatter torque curve. What is Ford's reply? Nothing as it is already a spray bar engine, dual inject, dual runner intake. yada yada.