Upper-chest shelf, locked on a track.
Touch high on the chest near the collarbone, not down by the sternum.
The Smith machine incline press runs the bar on a fixed track, so the sole variable is how hard your upper chest drives it off your collarbone line, no balancing act required. That locked path means you can chase failure on upper-chest work without a spotter, twisting the bar into the rack hooks whenever a rep gets ugly. Your shoulders assist off the chest, but a smart bench position keeps the pecs in charge.
Line the bar up over your upper chest at the bottom of the rep, then lie down and check before loading plates. Since the bar can't move to you, the bench position is your entire setup.
No, it just does a different job. The track carries the stabilising work so your chest can push closer to failure safely, which is exactly what you want from a hypertrophy press. Keep a free-weight press in the week too.
The bar path is fixed, so if the bench is misplaced the machine wins the argument. Shift the bench until the bar touches near your collarbone with your forearms vertical, and the press will smooth out.
