Oh man, I did this exact thing last year. The trick is finding the ceiling joist, absolutely do not just screw into drywall. I used a stud finder to mark it, then drilled pilot holes for some serious three inch wood screws. Holds my cast iron stuff without even a wobble.
Mounting to a joist is overkill and makes a huge mess of your ceiling. Heavy duty drywall anchors are way easier and hold plenty of weight. You also get more flexibility on where to put it instead of being stuck on a joist line.