I've done a few sets, and the SAFE way to strip them is media blasting (walnut shell or baking soda). Many chemicals have bad reactions with magnesium, and will distort or eat at the wheel.
If you only want to do this one time (hint) , primer and paint the entire wheel to completely seal it. If you don't, the mag will gas-off and you will have bubbles and holes that will start to form under the paint after time, especially in damp climates.
The wheels were originally a semi-gloss silver that Porsche has in their color charts from 1971. Many powdercoaters have similar colors.
Your space saver should be a 5 X 130mm pattern too.
The center caps are the early Porsche 3-prong style, just like the Fuchs use. They are listed on e-bay all the time, or new ones at
www.performanceproducts.com under Porsche parts.
Hope this helps, good luck !
Darrell