You want up-right comfort? This conversion cost me $65. North Road bars, decent MTB levers (Avid SD-7), and an adjustable stem. The Brooks B-67 cost another $85 incl S&H. Lots of arthritis, bad back and carpal tunnel issues. I've ridden several centuries and routinely go 50 - 80 miles on any given day. I rack up between 120 and 180 miles/week. The bars are currently even with the saddle instead of above, as in the second pic. Also, this is not a slow bike although it looks a little fuddy-duddy. It really covers ground.
The bar-ends go right in and work fine. This may work for you. Good luck.

before:http://i6.tinypic.com/1z1wy9s.jpg
after:http://i6.tinypic.com/1z1wz1d.jpg