I've seen A LOT of posts about making HP with a 318-So why is it so ???

I kept the original 318 block and crank from my Duster but the block needs machining (bores are super worn). I'll build it some day for a cruiser with emphasis on gas mileage but still decent HP. Flat-top pistons and aluminum heads most likely if it's going in an A-body, with a typical modern 260-270 adv. duration HFT cam. It was pretty fun to drive when it was running even though it burned a quart of oil every week or 2. I've built 2 360s since then, the increase in torque is massive but the 318s have a more "fun" powerband. Still decent torque down low if you build it right and they'll run up to 7k rpm a lot easier than a 360 if the valvetrain (and top end) is good for it.