I think if you get drop bars, you will want road levers. Not as much for the location of the levers, but for having the brake hoods to put your hands on. For many people, the hoods is the most comfortable position, with the most control, and your fingers are right near the levers. Normal road levers may not have the right leverage for your brakes though. Others will probably know that better than myself.

Not sure how you would convert the shifters to work on drops. (Maybe just go to friction shifting using bar-end levers?) I have an '88 Trek 900 with thumb shifters. I have some fairly long curved bar-ends on it to give me alternate hand postions. My favorite position seems to be grasping the closer end of the bar end extensions, which approximates grasping the hoods on my road bike, though with my arms a bit wider.

Port Bolivar by Yo Spiff, on Flickr