Methinks there will be as many different answers as there are posters to this thread. Because it is through the interpretation of the givens, and the experiences of the builder or cam chooser guy that profiles are determined. So, as far as my ideas... The cam choice in a NA engine is dependant on a bunch of factors. Port volume, length, and shape (from the back of the valve to the throttle blades of the carb); piston speed (both peak and mean); carburetor type and size; header/exh manifold designs; exhaust system; chamber size and design; piston crown design... Then, I also consider the car, the transmission and gearing, the intended use, the owner's talents and budget, the desired result, and how much ciontrol I have over the rest of the build. Because if the hone job sucks, or the valve job is the best Aerohead can do, I may need a cam to make more power to cover the losses that poor quality machining produces. (A better built engine doesnt need as much cam to make the same power..) That's how I determine which cam I want to use in someone else's engine. Basing anything on my personal vehicles or past successes IMO is very close to fruitless. Because there are so many variables day to day, that "your results may vary". Where the personal experience comes in is the way these parts work together, and to some extent the "you need X to run Y" that comes with having done it more than once or twice. And in that last part, we usually see disagreements. In the end, if the "done-by-green engine" makes 450hp with a certain design and the "done-by-blue engine" makes 450hp with a different design, overall opinions may not matter at all.
Now, you asked if your cam could make 400 hp. I think so, yes. But, it would need a shorter stroke, an intake tract that will let the engine believe the cam is bigger than it really is, and and exh that is designed just to make power at a certain rpm point, and higher rpm point. HP is torque times rotations per minute over a constant, so the more revolutions in that same time, the more power will be at the crank. IMO, Something smaller like a 318, with a set of well done smaller ports like a good set of 302s, a tight quench for good static compression, and less stroke and more rpm than a 4" arm engine would make that number with that cam. But it would do it at something like 5200. The 4" crank will reach the "magic" power point much lower in the rpm range, near 4000rpm, and that is why I think it will simply starve before it clears 400hp. It will make mad torque, but fail to make the hp.
