When I was poor (an apprentice), I got a bargain lot from a mail order company. It usually came out of the blue, you picked anything you wanted and sent the rest back. Anyway there was a dress which must have been around a size 20 when I was around a 10 (
), long, dark red and black and it was just coming up to Halloween. My sewing skills were a bit limited then so I just took the easiest option and cut the sides down. It must have looked fine because I later shortened it and wore it a few times. I have no memory of what the bust area was like since I had none at the time, but it must have worked out fine.
I suppose really it depends on the jacket styling, some times the simplest option usually works best (hacking off sides and shoulders). There again I would imagine a lot of people reading this will throw their hands up in horror and give you some sensible advice.