Radials will make it drive MUCH better, with no wander. They are the best choice if you're going to use the truck regularly. If you want a stock appearance for shows, and don't plan on driving it as a daily use vehicle, bias will be ok, buth they will not perform anywhere near as well as a modern radial.
Also, radial will be much cheaper, as virtually all bias construction tires are considered "specialty tires", and are priced higher than a comparable size/load range radial.
