If it was a true bowden cable, scaled to the model (like the device working the brakes on a bike, but smaller), then two, both pulling. If, as is likely, it will be something a bit different, then one. The outer guide sleeve should be free of sharp bends, reasonably rigid and supported. If the inner is a single moderately heavy wire rather than a bunch of strands and the right distance has been arranged at both ends to allow for a bit of swing (both servo and tiller describe arcs) there should be no problem, especially with a model of modest size and power.
If the original bit of bent wire does the job and is reasonably well hidden, it is quite possible that it could be the best solution. Just as long as its strong enough to do the job, and that none of the bends flex in use.