I would think all control cables & the upper brake line would need to be lengthened. you don't want to be stressing or binding the cables or brake line.
MotionPro makes custom cables. If they have cables for your bike, then you'd just need to figure out how much longer the new cables need to be, then they can use the stock cables as templates.
Barnett is another place that probably makes special order cables.
1981 KZ650-CSR. Competition, Sports & Road.