Looks nice! I don't know if this will help, but I offer it anyway. Description of the required placards can be found in the FAA Type certificate: http://www.douglasdc3.com/faa/a-669.pdf. Download the document a search for "placard." There are about 42 of them. I am also attaching a diagram of what instruments went where. It is not a perfect match for your panel, but it will get you going in the right direction. Have fun!
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