this is as you know a waffenrad, wartime bike, sure you could sandblast it, and paint it and you would have a old frame with a paintjob.I do not know how complete your bike is, but every part you buy will make your investement go up higher, in the end you will have a lot of money with poor resale value.

check for yourself- ebay.de, waffenrad

I am sorry to say that you can find complete bicycles of this type for very little money,

I have one simmilar that wasin better condition but the rims were rusted and a few pieces were missing,

I took out the hubs and the frame awaits going to the dump, my bike was not worth saving.

best of luck
mike in Finland