I went the other way: drop bars to trekking bars, to be nicer to my arthritic wrist.
The bike had Shimano Ultegra 3 x 9 with V-brakes. It was originally set up with "Travel Agents" (seen in Post #9 above), and the brakes worked really well.
The Ultegra RD has the same pull ratio as the XTR rear shifter. The FD was the problem; I settled on a Rivendell "Silver Shifter" (friction), which works quite well.
For brake levers, I got a pair of Paul "Love Levers". I still had to use the Travel Agents, but just as simple pulleys, not pull-ratio changers.
The cables had to be routed in a weird sort of way, but the whole system works nicely.
Good luck with your project!


Looks weird; works well.