You can't just change the straddle cable to a longer cable just because you need clearance. That cable is there to give the brakes a certain degree of mechanical advantage so that the brakes can be applied fairly easily without losing braking efficiency. If you install a longer cable you "could" run into a problem with applying the brakes and not having any brakes unless you squeeze the brakes really hard, the result of the longer cable is called having too little mechanical advantage, and there is a very small margin in this respect one way or the other beyond what the original brake spec'd that cable size for.

I forget, but there is about 5 to 6 different lengths of these cables available, the most you could do is go up one size longer than the factory spec'd and then you would still have to road test the bike real well to make sure the bike will stop fast and the amount of force to do so is not objectionable.