You can avoid having to buy new levers to go with the V-brakes (circumventing the problem of different cable-pull) by getting a QBP Travel Agent, which is basically a roller-cam which sits at end of the V-brake, replacing the Shimano 'noodle'. These work fine, are well made with a sealed bearing and basically last forever. You can't use 2mm cable, but then with V-brakes, you won't need to...
Ask at your LBS.