On my bike I use a Nitto Technomic stem and a 45 cm wide Nitto Randonneur handle bar. If you get a new stem and bar, just make sure the clamp diameter of the stem matches the bar.

Also, I believe if you change the brake levers to aero type it is supposed to help braking. Nashbar has a cheap set, but I prefer Tektro levers.

One caution, if you raise the bars too much you will have a longer reach down to the shifters...