x2. No power added, restricted intake choices (and really restrictive air cleaner...)
Here's my take... If you want a flat hood and you're using factory suspension and a motor plate you can make a little past 500hp, maybe a little more as it's run in that car. That's because whatever it makes on the dyno will be reduced when you stick an air filter housing and hood on the car. That doesn't make a difference with cubes, fuel, weather, anything else. You can only go so far down in the chassis with a K frame. Stick with a factory B wedge, stick a 5.75 crank in it with a decent set of heads, and work on fine tuning everything else on the car to maximize what it makes in it.
Otherwise - build a race car.