Brakes and RD will be fine with the Sora, FD probably not. Since it's indexed you would need a Shimano "road" FD to make it work. Note that the Shimano "MTB" FDs use a different cable pull.
Originally Posted by
bikemig
You could always use shimano bar end shifters. That's what I'm running on my drop bar mtb conversion. There's a lot to be said for running friction for the front crankset in any case.
Another +1 for bar-end shifters. That's the way I'd setup the bike pictured if drop bars are the goal.