You are confusing rod length with stroke.
To make a crank a "stroker" (more stroke that stock) the big end (End that attaches to crank) is relocated closer to the outside of the crank wheel so that it pushes it up farther and pulls it in farther are the crank rotates.
The "long rod" in this case 110 to 115 in length the big end of the rod remains in the same location as stock so the rod itself doesn't move any farther up or down, it is just simply longer. To keep the piston where it needs to be (5mm lower) the wrist pin location in the piston is raised, which lowers the piston in the bore. Hence why you cannot use a stock piston on a long rod motor. (Well, you could, but that's another huge can of worms!)
@ClaudeMachining fucks Eskimos, but he probably has a good diagram and probably active model of this.