Even though Banks may not make an exact fit package for your JD/460 chassis, you should still be able to "home brew" a headers and exhaust setup. If you don't live in an area that needs to be smog checked you can put on just about anything that will fit, but if you fall under an emissions check area you'll have to be careful that the setup meets requirements. Usually, if the headers have a California CARB certification they will meet local requirements.
I recommend headers that are ceramic coated. Those will last longer and run cooler since they keep the heat INSIDE the header tubes. You don't HAVE to go dual pipes. A single 3" pipe will give enough free-flow for a stock 460. If you currently have a catalytic converter and need to stay emissions compliant, you'll need to use a single pipe anyway.
Do your research and talk to a good exhaust bender. You can probably put together your own setup for half the price of the Banks.