I just cleaned up the original spokes for a build I'm doing. I used the red "metal" scrub pad you can find at auto stores and Ace Hardware locations. Use a little WD-40, PB Blaster, or the like, and sand them down. It goes quickly, and you will be surprised at the beautiful finish you get. I'm not sure if they will hold up to weather and salt after this, but the spokes are at least ready for powder coat (clear, black, grey, etc), and you know you have the quality of original spokes.
Camelman