You can buy a complete banshee cheaper than building one. If your wanting another machine. The down side is you dont know what kind of work has been done. Just cause you pay for a good looking machine doesnt mean you actually get one. Some people have no clue on how to build an engine.
You could always turn yours in to a dune machine. 4mill crank, dune ported cylinders, cpi pipes, PWK 333 carbs, +4 swing arm. It would be a fun general riding machine. If your going to build more twards a drag banshee then you should probably start out fresh with a frame and build up from there. You wont be using much from a complete banshee.