I think 3 out of 4 is about right, but it would make better sense if they gave you some idea of how many stitches you should end up with. I find that it can be trial and error. It is a comfort, though, that if you find you didn't do enough or did too many, the stitches can be pulled out without any real consequence to the sweater (though not to your time).
Maybe you can find a pattern that is similar to yours and see about how many stitches should be picked up.
A 36" needle is pretty long. I really believe that you'll have plenty of room.