Zero balance is generally desirable, but not necessary on a street motor. Given the components you have, it may not be possible without adding weight (Mallory metal) to the crank. For your application, it would be money wasted. IMO. Just take care that you balance the motor with the actual flywheel, balancer, crank, rods, bearings, rings, pins, locks (if used) and pistons. Make sure the balancer and flywheel have the same imbalance factor.
If I remember right your car is a 65 or 66. If so, there are fitment problems with the TKO. For proper driveline angle, you must raise the tunnel about 2" (cutting anf fabricating is needed). Unless you are making lots of power and plan to run lots of tire or slicks, the TKO isn't needed. I am making somewhere in the area of 450 fwhp and can run a 245/50-16 tire without fear of breaking my Motorsport T-5 (2.95 first gear). Generallky speaking, it is tough to get enough street tire on an early model to get all the power to the pavement. So, breakage is seldom an issue.