FWIW, I personally prefer the square butt on an N frame and don't have trouble concealing it, so I'd leave it for the time being. You can always grind it down later.

As for the barrel, I think on a variety of levels you are better off keeping it at around 3". There's the slight increase in performance, the improved appearance, and ultimately the fact that if you finish it and decide to sell, folks on this site will gobble it up if it's a 3", but less so if it's a 2". Note: I carry a 3" 629 every day, and it's my favorite gun. Despite being a round butt, otherwise it's just the perfect size for me.