I've read that other people were able to use their stock cables; however, my stock pull cable ('77 CB750) was too long, so I shortened it about 1/2". I do have few pieces of advice, though.
Once you get the cables all set, attach them to the carbs before you attach the carbs to the insulators. It's nearly impossible to attach the cables after the carbs are mounted.
I had a tough time trying to get my CR29's to mount into the insulators. I purchased new insulators, and all went well.
Unlike the stock carbs, the idle adjuster is in the center, and it's a pain to adjust because you have to lift the tank everytime you do it. MRieck outlined how he made a remote adjuster:
Keihin CR Thread. I haven't tried this yet, but I want to do it sometime.
You may have already figured out that the CR29's don't use a choke cable.