318 cam shaft selection/upgrade for stock engine

That is true of the dual diaphragm units.
Not of the Larger single diaphragm 73 up units.
And the cure for the little ones is a 15/16 M/C . When the boost goes away you will hardly notice it.
But my 73Dart booster works just fine with a 230@050 cam that idles right around 10 ish in neutral (4speed car).
BTW, I'm not encouraging you to buy more cam than you need; Just to entertain a bigger cam than one that idles at 18. If you are looking for performance, there are probably 2 or 3 cam sizes between stock and too-big-for-that-booster.And another 2 sizes until the bigger booster starts to go soft.
But,if you are at stock CR,you will run out of compression first.There's just not a lot of room before the take-off gets soggy. And then you need to increase your stall-speed in compensation, and shortly after that, you will need rear gears. So, it's kindof a balancing act,between adding performance at higher rpm with a bigger cam, and loosing bottom end to get it. The only way to get the bottom back is with compression.And when that gets too high , you run outta room with insufficient octane to suppress detonation.
Everybody is pushing and shoving,and then you run outta cubic inches and get to stroke that thing,lol,and start over.By everybody,I mean;compression,cam, octane,TC, gears, and finally, cid. And eventually you run outta head.